Synthesis of Alkynylselenides under Visible-Light Irradiation Using the Ionic Liquid [BMIm]BF₄ as a Solvent

Abstract

In this work, a visible-light-driven synthesis of alkynyl selenides using [BMIm]BF₄ as an environmentally friendly solvent and without the addition of metal catalysts, photosensitizers, directing-groups, or bases is reported. The target compounds were obtained in moderate to good yields with good functional group tolerance by the reaction of diorganoyldiselenides with 1-bromoalkynes proceeding through a radical mechanism.

Keywords:
ionic liquids; environmentally friendly synthesis; visible-light; organochalcogen

Introduction

Visible-light promoted reactions have emerged as a remarkable and powerful tool to provide greener and milder transformations in organic synthesis, leading to a wide range of organic reactions that are conducted at room temperature and easily operated.¹ Moreover, the light-emitting diodes that are able to promote photochemical reactions under visible-light are inexpensive, sustainable lighting sources with broad commercial availability,² which makes this approach very attractive from an environmental and economic perspective.

In this context, the continuous search for new synthetic routes that can reduce/minimize the generation of waste and side-products and that, in some way, fit within the principles of green chemistry is necessary.³ In this way, for a long time, ionic liquids have attracted the interest of the scientific community and even industry,⁴ as these organic salts can exhibit several applications in organic synthesis,⁵ CO₂ capture,⁶ catalysis,⁷ biochemistry,⁸ and others. In particular, they have often been used to replace conventional solvents in organic reactions⁹ due to their unique physical properties such as high thermal stability, low volatility, low flammability, and negligible vapor pressure.¹⁰ In addition, the fundamental structure of ionic liquids has offered many combinations of organic cations and organic or inorganic anions in order to specifically model them for different sustainable applications.¹¹

As part of the sophisticated organochalcogen chemistry found in biological¹² and materials sciences,¹³ alkynyl chalcogenides are useful and versatile synthetic intermediates in hydrohalogenation,¹⁴ cycloaddition,¹⁵ cross coupling,¹⁶ A³-coupling,¹⁷ chalcogenoesters synthesis,¹⁸ and cyclization reactions,¹⁹ playing an important role in the synthesis of bioactive heterocyclic compounds described as anti-cancer,¹⁵ anti-alzheimer’s,¹⁹ and antioxidant¹⁹ agents (Scheme 1).

Scheme 1
Selected synthetic applications of alkynyl chalcogenides.

A convenient method for the synthesis of alkynyl chalcogenides involves the reaction between diorganoyl dichalcogenides and terminal alkynes. However, this approach often requires reducing agents²⁰ or metal catalysts, such as copper,²¹ iron,²² or silver²³ (Scheme 2a, i). Recently, some metal-free strategies under base-catalyzed conditions (catalytic K₃PO₄ or CsOH) were described,²⁴ but these methodologies are restricted to the synthesis of alkynyl tellurides (Scheme 2a, ii). Alternatively, considering the number of works about carbon-chalcogen bond formation under visible light irradiation,²⁵ photochemistry becomes a promising tool to expand the synthesis of alkynyl chalcogenides in an eco-friendly pathway. The first step toward the photoinduced synthesis of alkynyl chalcogenides was taken by Collins and co-workers,²⁶ who reported an elegant transition-metal photoredox catalysis for the synthesis of alkynyl sulfides using thiols and 1-bromoalkynes in the presence of a nickel catalyst and 4CzIPN as a photosensitizer under blue light emitting diode (LED) irradiation (Scheme 2b). Interestingly, the use of 1-bromoalkynes in this methodology was essential to avoid the reduction of the C≡C bond and the subsequent formation of vinyl chalcogenides as side-products, which are usually observed in previous photoinduced reactions of terminal alkynes with thiols¹⁹ or diorganoyl dichalcogenides under visible light irradiation.²⁷ More recently, the amino group ortho-assisted synthesis of alkynyl sulfides using 2,2’-diaminodisulfides and terminal alkynes or 1-bromoalkynes proved to be an efficient strategy towards the formation of the Csp–S bond under visible light (Scheme 2c).²⁸

Scheme 2
Synthetic strategies for the synthesis of alknyl chalcogenides. (a) Typical synthesis of alkynyl chalcogenides from terminal alkynes; (b) photoinduced synthesis of alkynyl sulfides from 1-bromoalkynes and thiols; (c) photoinduced synthesis of alkynyl sulfides from 1-bromoalkynes and diorganoyl disulfides using directing-group strategy; (d) this work: photoinduced synthesis of alkynyl selenides from 1-bromoalkynes in ionic liquids.

In this context, considering the well-established homolytic cleavage of diorganoyl dichalcogenides under visible light to produce chalcogen centered-radicals²⁹ and the use of 1-bromoalkynes in order to maintain the valuable C≡C bond in photoinduced processes, herein, we report the synthesis of alkynylselenides under visible-light irradiation using the ionic liquid [BMIm]BF₄ as an environmentally friendly solvent (Scheme 2d). The developed methodology avoided the requirement of directing-group strategies and allowed the synthesis of alkynyl selenides in moderate to good yields. Furthermore, [BMIm]BF₄ played a crucial role as the reaction media to convert vinylic side-products into the desired alkynyl selenides.

Results and Discussion

Our reaction study started by using (bromoethynyl) benzene (1a) and diphenyldiselenide (2a) as model substrates and the reaction was carefully monitored by gas chromatography mass spectrometry (GC-MS). Initially, the stoichiometric relationship between 1a and 2a was evaluated (for details, see Supplementary Information (SI) section, Table S1). The best condition was found when 3.0 equivalents of 1a and 1.0 equivalent of 2a reacted under blue LED irradiation (100 W) in dichloromethane (DCM) after 1 h, with 68% conversion of 2a into the desired product phenyl(phenylethynyl)selane (3a) along with the vinylic side-product 4 (m/z = 418) in a 69:31 ratio, respectively (Table 1, entry 1). To improve the conversion of 2a and the reaction selectivity, other lightning sources were evaluated (Table 1, entries 2-4), but unsatisfactory conversions of 2a were obtained. Next, the reaction was performed under blue LED (100 W) irradiation in other polar aprotic solvents (Table 1, entries 5-9), such as tetrahydrofuran (THF), dimethylformamide (DMF), and dimethylsulfoxide (DMSO). A moderate conversion of 2a was observed in DMF, with a good ratio of the desired product 3a and the vinylic side-product 4 (Table 1, entry 5). Alternatively, the reaction performed in THF showed an excellent conversion of 2a, but the reaction was not selective (Table 1, entry 6). Longer reaction times in DMF provided good conversions of 2a with excellent selectivity (Table 1, entries 7 and 8). Similarly, a good conversion of 2a was obtained in DMSO, but the selectivity was not improved (Table 1, entry 9).

Table 1
Optimization of the reaction conditions for the synthesis of 3a

entrya	Lamp	Solvent	time / h	Conversion of 2ab / %	Ratio (3a:4)c
1	blue 100 W	DCM	1	68	69:31
2	blue 50 W	DCM	1	8	100:0
3	white 100 W	DCM	1	16	56:44
4	UVA 50 W	DCM	1	0	–
5	blue 100 W	DMF	1	47	89:11
6	blue 100 W	THF	1	94	62:38
7	blue 100 W	DMF	4	72	93:07
8	blue 100 W	DMF	24	72	97:03
9	Blue 100 W	DMSO	24	78	69:31
10d	blue 100 W	[BMIm]BF4	24	98	90:10
11d	blue 100 W	[BMIm]PF6	24	98	43:57
12e	blue 100 W	[BMIm]BF4	24	82	81:19
13f	blue 100 W	[BMIm]BF4	24	60	70:30

• ^a
  Reaction conditions: 1a (0.3 mmol), 2a (0.1 mmol), solvent (1 mL), under argon atmosphere; ^b,^cdetermined by GC-MS of the crude reaction mixture; ^dreaction conditions: 1a (0.3 mmol), 2a (0.1 mmol), solvent (1 g); ^ereaction conditions: 1a (0.3 mmol), 2a (0.1 mmol), solvent (0.5 g); ^freaction conditions: 1a (0.3 mmol), 2a (0.1 mmol), solvent (1.5 g). DCM: dichloromethane; THF: tetrahydrofuran; DMF: dimethylformamide; DMSO: dimethylsulfoxide.

In order to selectively produce 3a under environmentally benign reaction conditions, we hypothesized that ionic liquids based on the imidazolium cation and tetrafluoroborate (BF₄^–) anion could serve as an ideal reaction media in our methodology. In 2005, Ranu and Jana³⁰ demonstrated that this class of ionic liquids could effectively act as a catalyst and solvent in debromination reactions of alkyl and alkenyl vicinal-dibromides, affording the respective alkenes and alkynes in high yields.³¹ With this in mind, and in order to convert the undesired vinylic side-product 4 into 3a by debromination, we performed a reaction in the ionic liquid [BMIm]BF₄, which gratifyingly led to an excellent conversion of 2a with high selectivity for the desired product 3a (Table 1, entry 10). Furthermore, the use of the ionic liquid [BMIm]PF₆ as the solvent did not favor the reaction selectivity (Table 1, entry 11), indicating an important role of the BF₄ anion in our methodology. Finally, lower or higher amounts of [BMIm]BF₄ did not improve the reaction efficiency (Table 1, entries 12 and 13).

With the optimized reaction conditions in hand (Table 1, entry 10), we then evaluated the reaction scope of this photoinduced process. Unfortunately, although high conversion and selectivity were achieved during the reaction optimization study for the synthesis of 3a, this compound could not be cleanly isolated by column chromatography from the remaining mixture of diphenyldiselenide 2a and the vinylic side-product 4, so we decided to use methoxy-substituted diaryl diselenides 2 during the reaction scope to benefit the purification processes (Scheme 3). Initially, bromoethynylbenzene (1a) and arylbromoalkyne derivatives bearing electron-donating or electron-withdrawing groups on the benzene ring successfully reacted with 1,2-bis(4-methoxyphenyl) diselane (2b), affording the respective alkynylselenides 3b-3h in moderate to good yields. The reaction also tolerated bromoalkynes containing naphtalene derivatives or heteroaromatic groups in comparable yields (Scheme 3, 3i and 3j). Sterically hindered 1,2-bis(2-methoxyphenyl) diselane (2c) also proved to be a suitable reaction partner in this transformation (Scheme 3, 3k). Also, vinyl or alkyl bromoalkyne derivatives were well tolerated, but modest yields and longer reaction times were required, which was probably related to a weakly radical stabilization on these substrates (Scheme 3, 3l-3n). It is noteworthy that an alkynylsulfide derivative could also be synthesized through this photoinduced process (Scheme 3, 3o). This reaction required the use of a 200 W blue LED to proceed well, which is a reasonable result considering the higher relative energy of the S-S bond in comparison to the Se-Se bond.³¹ Finally, it is important to mention that the reaction did not work for bromoalkynes containing strong electron-donating or withdrawing groups such as amino, nitro, cyano, and pyridyl (Scheme 3, 3p-3s).³²

Scheme 3
Scope of the photoinduced synthesis of selenoalkynes. ^aReaction conditions: 1 (0.3 mmol), 2 (0.1 mmol), [BMIm]BF₄ (1.0 g), under blue LED (100 W) and argon atmosphere for the respective reaction times indicated. ^bIsolated yields. ^cProduct observed by GC-MS in a 90:10 (3a/4a) ratio after 98% conversion of 2a. ^dIsolated yield after 100% conversion of 2b, in a 100:0 ratio of 3b:4b determined by GC-MS of the crude reaction mixture. ^eReaction carried out with 2.7 mmol of 2b and 8.1 mmol of 1a in [BMIm]BF₄ (27.0 g). ^fReactions carried out during 48 h. ^gBlue LED (200 W).

In order to give insights about the reaction mechanism, some control experiments were performed under the optimized reaction conditions for the synthesis of 3a (Scheme 4). The addition of the radical inhibitor (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) almost completely inhibited the reaction, indicating a radical mechanism (Scheme 4a). Moreover, a reaction performed in the dark did not produce 3a, which confirmed the fundamental effect of light irradiation in our methodology (Scheme 4b).

Scheme 4
Control experiments for the synthesis of 3a. (a) Radical trapping experiment. Reaction conditions: 1a (0.3 mmol), 2a (0.1 mmol), TEMPO (4.0 equiv.), [BMIm]BF₄ (1.0 g), under blue LED (100 W) and argon atmosphere for 24 h. (b) Reaction performed in dark. 1a (0.3 mmol), 2a (0.1 mmol), [BMIm]BF₄ (1.0 g) under argon atmosphere (reaction flask covered with aluminum foil) for 24 h.

Based on these results, we proposed a plausible mechanism for the photoinduced synthesis of alkynylselenides 3 in [BMIm]BF₄ (Scheme 5). Initially, diaryldiselenide 2 undergoes a reversible Se–Se bond homolytic cleavage due to the light irradiation.²⁹ Then, a radical addition between arylselenium radical species and bromoalkyne 1 takes place to produce a vinylic radical intermediate 5. At this point, the desired product 3 can be directly obtained by bromine radical elimination³¹ from intermediate 5 (Scheme 5, pathway A). Conversely, this intermediate can undergo a bromine radical addition to generate the respective vinylic dibromide side-product 4 (Scheme 5, pathway B). Based on previous literature,³⁰ a debromination reaction can occur from 4 in the presence of [BMIm]BF₄, leading to vinylic carbanion species 6, which is able to produce 3 with concomitant regeneration of [BMIm]BF₄.

Scheme 5
Plausible mechanism for the photoinduced synthesis of alkynylselenides 3 in [BMIm]BF₄.

Conclusions

In conclusion, a low-cost, environmentally benign and easily workable methodology for the photoinduced synthesis of selenoalkynes was developed. Even if moderate to good yields were obtained in the reaction scope investigation, we highlight that this methodology benefits from mild conditions and the inherent absence of transition-metals, photosensitizers, or directing-groups to promote a challenging photoinduced Csp–Se bond formation. We also hope that this work may provide useful insights into the use of ionic liquids as sustainable catalysts/reaction media in organochalcogen chemistry.

Experimental

Unless otherwise stated, all reagents were purchased from commercial suppliers (Sigma-Aldrich, Steinheim, Germany) and used without further purification. DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), MeCN (acetonitrile), THF (tetrahydrofuran) and DCM (dichloromethane) were purified and dried under classical methods.¹ Solvents used in liquid-liquid extraction and as eluents for chromatographic purification were distilled before use. The reactions were monitored by thin-layer chromatography (TLC) using silica gel 60 F₂₅₄ aluminum sheets, and the visualization of the spots were done under UV light (254 nm), stained with iodine, or by the mixture between 5% of vanillin in 10% of H₂SO₄ and heat as developing agents. Column chromatography was performed on silica gel (230-400 mesh). ¹H and ¹³C nuclear magnetic resonance (NMR) were recorded on 400 MHz spectrometer Varian Inova 400 and Bruker Avance 400. Chemical shifts (δ) are expressed in ppm downfield from tetramethylsilane (TMS) as internal standard in spectra made in CDCl₃. Coupling constants are reported in Hz. Hydrogen coupling patterns are described as singlet (s), doublet (d), triplet (t), quartet (q), quintet (quint), doublet of doublets (dd), doublet of doublet of doublets (ddd), doublet of triplets (dt), multiplet (m) and broad signal (bs) as soon as appears. Melting points were recorded on a Stuart Scientific melting point apparatus SMP3. High resolution mass spectra (HMRS) were recorded on a Micromass Q-Tof spectrometer (Milford, United States), using electrospray ionization (ESI).

General procedure for the synthesis of alkynylselenides 3a-3n and alkynylsulfide 3o

In a dried glass tube under argon atmosphere, [BMIm]BF₄ (1.0 g) was added and degassed for 20 min at room temperature. After this time, bromoalkyne 1 (0.3 mmol) and diaryldichalcogenide 2 (0.1 mmol) were added. Under argon atmosphere, the reaction mixture was stirred in the photoreactor (blue LED, 100 W) at room temperature for 24 h for the synthesis of 3a-3j, 3l and 3m and 48 h for the synthesis of 3k, 3n and 3o (the respective synthesis of alkynylsulfide 3o was performed using a blue LED 200 W). After the completion of the reaction, hexane/ethyl acetate (90:10 v:v, 5.0 mL) was added to the glass tube. After vigorous stirring, two layers were generated, and the upper layer containing the organic solvents was collected and this process was repeated until complete extraction of the desired product 3 (monitored by TLC). The collected organic phase was concentrated under reduced pressure and further purified by preparative thin layer chromatography on silica gel to give the desired products 3b-3o.

(4-Methoxyphenyl)(phenylethynyl)selane (3b)³³

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 56% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.53 (d, 2H, J 8.9 Hz), 7.47-7.44 (m, 2H), 7.32-7.29 (m, 3H), 6.88 (d, 2H, J 8.9 Hz), 3.79 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.5, 131.9, 131.7, 128.4, 128.3, 123.1, 118.3, 115.4, 101.5, 70.4, 55.4.

(4-Methoxyphenyl)(p-tolylethynyl)selane (3c)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 43% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.52 (d, 2H, J 8.9 Hz), 7.36 (d, 2H, J 7.9 Hz), 7.11 (d, 2H, J 7.9 Hz), 6.88 (d, 2H, J 8.9 Hz), 3.79 (s, 3H), 2.34 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.3, 138.6, 131.66, 131.65, 129.0, 120.2, 118.5, 115.3, 101.6, 69.2, 55.3, 21.5; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) d 260.83; HRMS (ESI) m/z [M⁺] calcd. for C₁₆H₁₄OSe, 302.0210; found, 302.0201.

((4-Ethylphenyl)ethynyl)(4-methoxyphenyl)selane (3d)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 63% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.52 (d, J 8.9 Hz, 2H), 7.38 (d, J 8.2 Hz, 2H), 7.14 (d, J 8.2 Hz, 2H), 6.87 (d, J 8.9 Hz, 2H), 3.79 (s, 3H), 2.64 (q, J 7.6 Hz, 2H), 1.22 (t, J 7.6 Hz, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.3, 144.9, 131.8, 131.6, 127.8, 120.4, 118.5, 115.3, 101.7, 69.2, 55.3, 28.8, 15.3; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 260.90; HRMS (ESI) m/z [M⁺] calcd. for C₁₇H₁₇OSe, 316.0361; found, 316.0351.

(4-Methoxyphenyl)(m-tolylethynyl)selane (3e)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 35% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.53 (d, J 8.8 Hz, 2H), 7.31-7.24 (m, 2H), 7.23-7.17 (m, 1H), 7.18-7.10 (m, 1H), 6.88 (d, J 8.8 Hz, 2H), 3.80 (s, 3H), 2.32 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.4, 138.0, 132.2, 131.7, 129.3, 128.7, 128.2, 123.0, 118.4, 115.3, 101.7, 69.8, 55.4, 21.2; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 261.33; HRMS (ESI) m/z [M⁺] calcd. for C₁₇H₁₆OSe, 302.0210; found, 302.0200.

((4-Fluorophenyl)ethynyl)(phenyl)selane (3f)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 52% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.52 (d, J 8.8 Hz, 2H), 7.46-7.42 (m, 2H), 7.02-6.98 (m, 2H), 6.88 (d, J 8.8 Hz, 2H), 3.80 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 162.5 (d, ¹J_C-F 250.0 Hz), 159.5, 133.7 (d, ³J_C-F 8.4 Hz), 132.0, 119.4 (d, ⁴J_C-F 3.5 Hz), 118.1, 115.6 (d, ²J_C-F 22.1 Hz), 115.3, 100.2, 70.1, 55.3; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 261.44; HRMS (ESI) m/z [M⁺] calcd. for C₁₆H₁₄OSe, 305.9959; found, 305.9951.

((4-Chlorophenyl)ethynyl)(phenyl)selane (3g)³⁴

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a pale-yellow solid in 30% yield; melting point 81-83 ºC; ¹H NMR (400 MHz, CDCl₃) δ 7.53 (d, J 8.9 Hz, 2H), 7.37 (d, J 8.7 Hz, 2H), 7.28 (d, J 8.7 Hz, 2H), 6.89 (d, J 8.9 Hz, 2H), 3.81 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.6, 134.3, 132.8, 132.1, 128.6, 121.7, 117.9, 115.4, 100.1, 71.8, 55.4.

4-(((4-Methoxyphenyl)selanyl)ethynyl)benzoate (3h)

The product was isolated by a preparative thin layer chromatography (hexane 95:5 ethyl acetate) as a yellow solid in 30% yield; mp 72-74 ºC; ¹H NMR (400 MHz, CDCl₃) δ 7.98 (d, J 8.4 Hz, 2H), 7.54 (d, J 8.8 Hz, 2H), 7.48 (d, J 8.4 Hz, 2H), 6.90 (d, J 8.8 Hz, 2H), 3.91 (s, 3H), 3.81 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 166.5, 159.7, 132.3, 131.1, 129.4, 129.3, 127.9, 117.7, 115.4, 100.7, 74.8, 55.4, 52.2; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 266.27; HRMS (ESI) m/z [M⁺] calcd. for C₁₇H₁₄O₃Se, 346.0108; found, 346.0101.

(4-Methoxyphenyl)(naphtalen-2-ylethynyl)selane (3i)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 44% yield; ¹H NMR (400 MHz, CDCl₃) δ 8.31 (d, J 8.2 Hz, 1H), 7.85-7.79 (m, 2H), 7.68 (d, J 7.2 Hz, 1H), 7.59 (d, J 8.8 Hz, 2H), 7.57-7.48 (m, 2H), 7.44-7.39 (m, 1H), 6.90 (d, J 8.8 Hz, 2H), 3.79 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.5, 133.4, 133.1, 131.9, 130.6, 128.8, 128.2, 126.8, 126.4, 126.2, 125.1, 120.9, 118.5, 115.3, 99.6, 75.2, 55.3; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 264.64; HRMS (ESI) m/z [M + H]⁺ calcd. for C₁₉H₁₅OSe, 339.0283; found, 339.0271.

3-(((4-Methoxyphenyl)selanyl)ethynyl)thiophene (3j)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 55% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.52 (d, 2H, J 8.9 Hz), 7.48 (dd, 1H, J 3.0, 1.2 Hz), 7.25 (dd, 1H, J 5.0, 3.0 Hz), 7.13 (dd, 1H, J 5.0, 1.2 Hz), 6.87 (d, 2H, J 8.9 Hz), 3.79 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.4, 131.9, 130.0, 129.6, 125.2, 122.3, 118.2, 115.3, 96.2, 69.8, 55.3; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 261.56; HRMS (ESI) m/z [M⁺] calcd. for C₁₃H₁₀OSSe, 293.9613; found, 293.9606.

(2-Mmethoxyphenyl)(phenylethynyl)selane (3k)³⁵

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 30% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.74 (dd, 1H, J 7.6, 1.6 Hz), 7.57-7.51 (m, 2H), 7.38-7.32 (m, 3H), 7.27-7.21 (m, 1H), 7.01 (td, 1H, J 7.6, 1.2 Hz), 6.87-6.81 (m, 1H), 3.89 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 155.7, 131.7, 128.5, 128.4, 128.3, 127.7, 123.3, 122.2, 118.5, 110.2, 104.2, 68.7, 55.9.

(Cyclohex-1-en-1-ylethynyl)(4-methoxyphenyl)selane (3l)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 25% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.46 (d, 2H, J 8.9 Hz), 6.87 (d, 2H, J 8.9 Hz), 6.18-6.12 (m, 1H), 3.80 (s, 3H), 2.23-2.05 (m, 4H), 1.71-1.52 (m, 4H); ¹³C NMR (100 MHz, CDCl₃) δ 159.2, 135.7, 131.3, 120.9, 118.8, 115.2, 103.7, 66.5, 55.3, 29.1, 25.6, 22.2, 21.4; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 258.56; HRMS (ESI) m/z [M⁺] calcd. for C₁₇H₁₄O₃Se, 292.0361; found, 292.0352.

(4-Methoxyphenyl)(4-phenylbut-1-yn-1-yl)selane (3m)

The product was isolated by a preparative thin layer chromatography (petroleum ether) as a yellow oil in 22%. ¹H NMR (400 MHz, CDCl₃) δ 7.38 (d, 2H, J 8.9 Hz), 7.32-7.28 (m, 2H), 7.25-7.19 (m, 3H), 6.83 (d, 2H, J 8.9 Hz), 3.80 (s, 3H), 2.88 (t, 2H, J 7.5 Hz), 2.71 (t, 2H, J 7.5 Hz); ¹³C NMR (100 MHz, CDCl₃) δ 159.2, 140.4, 131.4, 128.5, 128.4, 126.3, 118.5, 115.1, 102.1, 59.6, 55.4, 35.0, 22.6; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 256.91; HRMS (ESI) m/z [M⁺] calcd. for C₁₇H₁₆OSe, 316.0361; found, 316.0352.

(4-Methoxyphenyl)(oct-1-yn-1-yl)selane (3n)

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 27% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.46 (d, 2H, J 8.9 Hz), 6.86 (d, 2H, J 8.9 Hz), 3.80 (s, 3H), 2.40 (t, 2H, J 7.1 Hz), 1.63-1.51 (m, 2H), 1.46-1.36 (m, 2H), 1.35-1.21 (m, 4H), 0.89 (t, 3H, J 7.1 Hz); ¹³C NMR (100 MHz, CDCl₃) δ 159.2, 131.3, 118.8, 115.2, 103.2, 58.4, 55.4, 31.3, 28.7, 28.6, 22.6, 20.5, 14.1; ⁷⁷Se NMR (76 MHz, CDCl₃, (PhSe)₂ as internal standard δ = 463.00 ppm) δ 256.09; HRMS (ESI) m/z [M⁺] calcd. for C₁₅H₂₀OSe, 296.0674; found, 296.0668.

(4-Methoxyphenyl)(phenylethynyl)sulfane (3o)³⁶

The product was isolated by a preparative thin layer chromatography (hexane 97:3 ethyl acetate) as a yellow oil in 30% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.52-7.46 (m, 2H), 7.43 (d, 2H, J 8.8 Hz), 7.36-7.31 (m, 3H), 6.91 (d, 2H, J 8.8 Hz), 3.81 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) δ 159.0, 131.6, 128.9, 128.4, 128.3, 123.0 (2C), 115.0, 96.2, 77.2, 55.4.

Acknowledgments

The authors would like to acknowledge FAPERGS (PRONEX and RITEs-RS), CNPq (404503/2021-7, 308487/2021-4), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001, and INCT-CNM for the financial support.

Supplementary Information

Supplementary information (supplementary tables, NMR spectra) is available free of charge at http://jbcs.sbq.org.br as PDF file.

References

• ¹
  Stephenson, C. R. J.; Yoon, T. P.; MacMillan, D. W. C.; Light Photocatalysis in Organic Chemistry; Wiley-VCH: Weinheim, 2018 [Crossref]; Shaw, M. H.; Twilton, J.; MacMillan, D. W. C.; J. Org. Chem. 2016, 81, 6898 [Crossref]; Yoon, T. P.; Ischay, M. A.; Du, J.; Nat. Chem 2010, 2, 527 [Crossref]; Zhou, Q. Q.; Zou, Y. ; Lu, L. Q.; Xiao, W. J.; Angew. Chem., Int. Ed. 2019, 58, 1586 [Crossref]; Liu, Q.; Wu, L.-Z.; Natl. Sci. Rev 2017, 4, 359 [Crossref]; Xuan, J.; Xiao, W.-J.; Angew. Chem., Int. Ed. 2012, 51, 6828 [Crossref]; Marzo, L.; Pagire, S. K.; Reiser, O.; König, B.; Angew. Chem., Int. Ed. 2018, 57, 10034 [Crossref]; Hering, T.; Meyer, A. U.; König, B.; J. Org. Chem 2016, 81, 6927 [Crossref]; Ravelli, D.; Protti, S.; Fagnoni, M.; Chem. Rev 2016, 116, 9850 [Crossref].
• ²
  Bach, T.; Hehn, J. P.; Angew. Chem., Int. Ed. 2011, 50, 1000 [Crossref]; König, B.; Eur. J. Org. Chem 2017, 2017, 1979 [Crossref].
• ³
  Sheldon, R. A.; Green Chem 2005, 7, 267 [Crossref]; Simon, M.-O.; Li, C.-J.; Chem. Soc. Rev. 2012, 41, 1415 [Crossref]; Kharissova, O. V.; Kharisov, B. I.; González, C. M. O.; Méndez, Y. P.; López, I.; R. Soc. Open Sci 2019, 6, 191378 [Crossref]; Giofrè, S. V.; Tiecco, M.; Ferlazzo, A.; Romeo, R.; Ciancaleoni, G.; Germani, R.; Iannazzo, D.; Eur. J. Org. Chem 2021, 2021, 4777 [Crossref].
• ⁴
  Plechkova, N. V.; Seddon, K. R.; Chem. Soc. Rev. 2008, 37, 123 [Crossref]; Marrucho, I. M.; Branco, L. C.; Rebelo, L. P. N.; Annu. Rev. Chem. Biomol. Eng. 2014, 5, 527 [Crossref]; Greer, A. J.; Jacquemin, J.; Hardacre, C.; Molecules 2020, 25, 5207 [Crossref].
• ⁵
  Sawant, A. D.; Raut, D. G.; Darvatkar, N. B.; Salunkhe, M. M.; Green Chem. Lett. Rev. 2011, 4, 41 [Crossref]; Quereshi, Z. S.; Deshmukh, K. M.; Bhanage, B. M.; Clean Technol. Environ. Policy 2014, 16, 1487 [Crossref]; Itoh, T.; Chem. Rev. 2017, 117, 10567 [Crossref].
• ⁶
  Brennecke, J. F.; Gurkan, B. E.; J. Phys. Chem. Lett 2010, 1, 3459 [Crossref]; Ramdin, M.; de Loos, T. W.; Vlugt, T. J. H.; Ind. Eng. Chem. Res 2012, 51, 8149 [Crossref]; Aghaie, M.; Rezaei, N.; Zendehboudi, S.; Renewable Sustainable Energy Rev. 2018, 96, 502 [Crossref]; Albo, J.; Qadir, M. I.; Samperi, M.; Fernandes, J. A.; de Pedro, I.; Dupont, J.; Chem. Eng. J. 2021, 404, 126643 [Crossref].
• ⁷
  Steinrück, H.-P.; Wasserscheid, P.; Catal. Lett. 2015, 145, 380 [Crossref]; Ratti, R.; Adv. Chem. 2014, 2014, ID 729842 [Crossref]; McNeice, P.; Marr, P. C.; Marr, A. C.; Catal. Sci. Technol 2021, 11, 726 [Crossref].
• ⁸
  Egorova, K. S.; Gordeev, E. G.; Ananikov, V. P.; Chem. Rev 2017, 10, 7132 [Crossref]; Palkowski, L.; Karolak, M.; Skrzypczak, A.; Wojcieszak, M.; Walkiewicz, F.; Podemski, J.; Jaroch, K.; Bojko, B.; Materna, K.; Krysinski, J.; Molecules 2022, 27, 1974 [Crossref].
• ⁹
  Kumari, K.; Singh, P.; Mehrotra, G. K.; Int. J. Green Nanotechnol. 2012, 4, 262. [Crossref]
• ¹⁰
  Chiappe, C.; Pieraccini, D.; J. Phys. Org. Chem 2005, 18, 275 [Crossref]; Yang, Z.; Pan, W.; Enzyme Microb. Technol. 2005, 37, 19 [Crossref]; Villanueva, M.; Coronas, A.; García, J.; Salgado, J.; Ind. Eng. Chem. Res. 2013, 52, 15718 [Crossref]; Greaves, T. L.; Drummond, C. J.; Chem. Soc. Rev 2013, 42, 1096 [Crossref].
• ¹¹
  Donato, K. Z.; Donato, R. K.; Lavorgna, M.; Ambrosio, L.; Matejka, L.; Mauler, R. S.; Schrekker, H. S.; J. Sol-Gel Sci. Technol 2015, 76, 414 [Crossref]; Xue, Z.; Qin, L.; Jiang, J.; Mu, T.; Gao, G.; Phys. Chem. Chem. Phys. 2018, 20, 8382 [Crossref]; Vieira, M. O.; Monteiro, W. F.; Ferreira, T. M.; Domingos, J. B.; Dupont, J.; dos Santos, F. P.; Scholten, J. D.; J. Mol. Liq. 2021, 344, 11775 [Crossref].
• ¹²
  Mugesh, G.; du Mont, W.-W.; Sies, H.; Chem. Rev. 2001, 101, 2125 [Crossref]; Soriano-Garcia, M.; Curr. Med. Chem. 2004, 11, 1657 [Crossref]; Lenardão, E. J.; Santi, C.; Sancineto, L.; New Frontiers in Organoselenium Compounds; Springer: Heidelberg, 2018, p. 157 [Crossref].
• ¹³
  Mutlu, H.; Ceper, E. B.; Li, X.; Yang, J.; Dong, W.; Ozmen, M. M.; Macromol. Rapid Commun 2019, 40, 1800650 [Crossref]; Hoover, G. C.; Seferos, D. S.; Chem. Sci. 2019, 10, 9182 [Crossref].
• ¹⁴
  Comasseto, J. V.; Menezes, P. H.; Stefani, H. A.; Zeni, G.; Braga, A. L.; Tetrahedron Lett 1996, 52, 9687 [Crossref]; Sun, A.; Huang, X.; Synthesis 2000, 13, 1819 [Crossref]; Yang, A.; Chen, X.; Kong, W.; Xia, S.; Zheng, R.; Luo, F.; Zhu, V. ; Org. Biomol. Chem. 2013, 11, 2175 [Crossref].
• ¹⁵
  Mantovani, A. C.; Back, D. F.; Zeni, G.; Eur. J. Org. Chem 2012, 24, 4574 [Crossref]; Stefani, H. A.; Vasconcelos, S. N. S.; Manarin, F.; Leal, D. M.; Souza, F. B.; Madureira, L. S.; Zukerman-Schpector, J.; Eberlin, M. N.; Godoi, M. N.; Galaverna, R. S.; Eur. J. Org. Chem 2013, 18, 3780 [Crossref]; Song, W.; Zheng, N.; Li, M.; He, J.; Li, J.; Dong, K.; Ullah, K.; Zheng, Y. ; Adv. Synth. Catal 2019, 361, 469 [Crossref]; Cui, F.; Cheng, J.; Mo, Z.; Su, S.; Chen, Y.; Ma, X.; Tang, H.; Wang, H.; Pan, Y. ; Xu, Y. ; Org. Lett. 2018, 20, 925 [Crossref]; Narangoda, C. J.; Lex, T. R.; Moore, M. A.; McMillen, C. D.; Kitaygorodskiy, A.; Jackson, J. E.; Whitehead, D. C.; Org. Lett. 2018, 24, 8009 [Crossref].
• ¹⁶
  Savarin, C.; Srogl, J.; Liebeskind, L. S.; Org. Lett. 2001, 3, 91 [Crossref]; Stein, A. L.; Bilheri, F. N.; Zeni, G.; Chem Comm 2015, 51, 15522 [Crossref].
• ¹⁷
  de Oliveira, I. M.; Pimenta, D. C.; Zukerman-Schpector, J.; Stefani, H. A.; Manarin, F.; New. J. Chem. 2018, 42, 10118 [Crossref].
• ¹⁸
  Braga, A. L.; Rodrigues, O. E. D.; de Avila, E.; Silveira, C. C.; Tetrahedron Lett. 1998, 39, 3395 [Crossref]; Tiecco, M.; Testaferri, L.; Temperini, A.; Bagnoli, L.; Marini, F.; Santi, C.; Terlizzi, R.; Eur. J. Org. Chem. 2004, 16, 3447 [Crossref]; Baldassari, L. L.; Mantovani, A. C.; Senoner, S.; Maryasin, B.; Maulide, N.; Lüdtke, D. S.; Org Lett. 2018, 20, 5881 [Crossref].
• ¹⁹
  Manarin, F.; Roehrs, J. A.; Gay, R. M.; Brandão, R.; Menezes, P. H.; Nogueira, C. W.; Zeni, G.; J. Org. Chem. 2009, 74, 2153 [Crossref]; Lim, W.; Rhee, Y. H. A.; Eur. J. Org. Chem. 2013, 2013, 460 [Crossref]; Grimaldi, T. B.; Lutz, G.; Back, D. F.; Zeni, G.; Org. Biomol. Chem. 2016, 14, 10415 [Crossref]; Perin, G.; Roehrs, J. A.; Hellwig, P. S.; Stach, G.; Barcellos, T.; Lenardão, E. J.; Jacob, R. G.; Luz, E. Q.; ChemistrySelect 2017, 2, 4561 [Crossref]; Coelho, F. L.; Gil, E. S.; Gonçalves, P. F. B.; Campo, L. F.; Schneider, P. H.; Chem.-Eur. J. 2019, 25, 8157 [Crossref]; Perin, G.; Soares, L. K.; Hellwig, P. S.; Silva, M. S.; Neto, J. S. S.; Roehrs, J. A.; Barcellos, T.; Lenardão, E. J.; New J. Chem. 2019, 43, 6323 [Crossref].
• ²⁰
  Soares, L. K.; Silva, R. B.; Peglow, T. J.; Silva, M. S.; Jacob, R. G.; Alves, D.; Perin, G.; ChemistrySelect 2016, 1, 2009. [Crossref]
• ²¹
  Bieber, L. W.; da Silva, M. F.; Menezes, P. H.; Tetrahedron Lett. 2004, 45, 2735 [Crossref]; Godoi, M.; Ricardo, E. W.; Frizon, T. E.; Rocha, M. S. T.; Singh, D.; Paixão, M. W.; Braga, A. L.; Tetrahedron Lett. 2012, 8, 10426 [Crossref]; Mohamadi, E.; Movassagh, B.; Tetrahedron Lett. 2014, 55, 1613 [Crossref].
• ²²
  Godoi, M.; Liz, D. G.; Ricardo, E. W.; Rocha, M. S. T.; Azeredo, J. B.; Braga, A. L.; Tetrahedron Lett. 2014, 70, 3349. [Crossref]
• ²³
  Xavier, M. C. D. F.; Goldani, B.; Schumacher, R. F.; Perin, G.; Schneider, P. H.; Alves, D.; Mol. Catal. 2017, 427, 73. [Crossref]
• ²⁴
  Zou, K. B.; Qiu, R. H.; Fang, D. W.; Liu, X. Y. ; Xu, X. H.; Synth. Commun. 2008, 38, 2237 [Crossref]; do Sacramento, M.; Menezes, L.; Goldani, B.; Perin, G.; Silva, M. S.; Barcellos, T.; Alves, D.; New J. Chem. 2019, 43, 11091 [Crossref].
• ²⁵
  Wiimer, A.; König, B.; Beilstein J. Org. Chem. 2018, 14, 54 [Crossref]; Srivastava, V.; Singh, P. K.; Srivastava, A.; Singh, P. P.; RSC Adv. 2020, 10, 20046 [Crossref]; Dalberto, B. T.; Schneider, P. H.; RSC Adv. 2020, 10, 10502 [Crossref]; Rafique, J.; Rampon, D. S.; Azeredo, J. B.; Coelho, F. L.; Schneider, P. H.; Braga, A. L.; Chem. Rec. 2021, 21, 2739 [Crossref].
• ²⁶
  Santandrea, J.; Minozzi, C.; Cruché, C.; Collins, S. K.; Angew. Chem., Int. Ed. 2017, 56, 12255. [Crossref]
• ²⁷
  Dénès, F.; Pichowicz, M.; Povie, G.; Renaud, P.; Chem. Rev. 2014, 114, 2587 [Crossref]; Zalesskiy, S. S.; Shlapakov, N. S.; Ananikov, V. P.; Chem. Sci. 2016, 7, 6740 [Crossref].
• ²⁸
  Reddy, M. B.; Anandhan, R.; Chem. Commun. 2020, 56, 3781 [Crossref]; Ye, R.; Ruan, H.; Xu, H.; Li, Z.; Meng, L; Wang, L.; Org. Chem. Front. 2021, 8, 5345 [Crossref].
• ²⁹
  Heiba, E. I.; Dessau, R. M.; J. Org. Chem. 1967, 32, 3837 [Crossref]; Ogawa, A.; Yokoyama, K.; Yokoyama, T.; Masawaki, N.; Kambe, N. S.; Sonoda, N.; J. Org. Chem. 1991, 56, 5721 [Crossref]; Ogawa, A.; Yokoyama, K.; Obayashi, R.; Han, L.-B.; Kambe, N.; Sonoda, N.; Tetrahedron Lett. 1993, 49, 1177 [Crossref]; Weber, A. C. H.; Coelho, F. L.; Affeldt, R. F.; Schneider, P. H.; Eur. J. Org. Chem. 2018, 47, 6738 [Crossref]; Kobiki, Y.; Kawaguchi, S.; Ogawa, A.; Tetrahedron Lett. 2013, 54, 5453 [Crossref].
• ³⁰
  Ranu, B. C.; Jana, R.; J. Org. Chem. 2005, 70, 8621. [Crossref]
• ³¹
  Zhou, Q.-Q.; Guo, W.; Ding, W.; Wu, X.; Chen, X.; Lu, L.-Q.; Xiao, W.-J.; Angew. Chem., Int. Ed. 2015, 54, 11196. [Crossref]
• ³²
  Kaur, D.; Sharma, P.; Bharatam, P. V.; J. Mol. Struct.: THEOCHEM 2007, 810, 31. [Crossref]
• ³³
  Movassagh, B.; Yousefi, A.; Momeni, B. Z.; Heydari, S.; Synlett 2014, 25, 1385. [Crossref]
• ³⁴
  She, C.; Yu, P.; Luo, X.; Tian, Z.; Zhang, W.; Chin. J. Appl. Chem. 2017, 34, 1134. [Crossref]
• ³⁵
  Mohan, B.; Park, J. C.; Park, K. H.; ChemCatChem 2016, 8, 2345. [Crossref]
• ³⁶
  Feng, Q.; Huang, H.; Sun, J.; Org. Lett. 2021, 23, 2431. [Crossref]

Edited by

Editor handled this article: Brenno A. D. Neto (Associate)

Publication Dates

• Publication in this collection
  31 Mar 2023
• Date of issue
  2023

History

• Received
  25 July 2022
• Accepted
  27 Oct 2022