Synthesis of <i>N,O</i>-Type Inherently Chiral Calix[4]arenes Substituted on the Lower Rim and their Organocatalysis Properties

Chang, Ming-Liang; He, Yong; Zhou, Jing; Li, Shao-Yong

doi:10.21577/0103-5053.20160307

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Journal of the Brazilian Chemical Society

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Articles • J. Braz. Chem. Soc. 28 (08) • Aug 2017 • https://doi.org/10.21577/0103-5053.20160307 copy

Synthesis of N,O-Type Inherently Chiral Calix[4]arenes Substituted on the Lower Rim and their Organocatalysis Properties

Authorship SCIMAGO INSTITUTIONS RANKINGS

This work presented the first study of organocatalytic behaviors of inherently chiral calix[4]arenes substituted at the lower rim. A pair of N, O-type enantiomers based on inherently chiral calix[4]arenes substituted at the lower rim were readily synthesized and applied to catalyze Henry reaction between aromatic aldehydes and nitromethane. Their organocatalytic reaction can afford the desired products in excellent yields (up to 99%) but poor enantioselectivities (up to 7.5% ee).

Keywords:
inherently chiral; calix[4]arene; asymmetric catalysis; Henry reaction


entry^a a The reaction was performed with 0.6 mmol 4-nitrobenzaldehyde and 6 mmol nitromethane in 4 mL solvent;	Catalyst	Solvent	Temperature / ºC	time / h	Configuration	Yield^d d isolated yield; / %	ee^e e enantiomeric excess was determined by HPLC using a Chiracel OD-H column. The absolute configurations of all products were determined by comparing the retention time from HPLC data on the products with those in the literature data.19-21 / %
1	5a	CH₃CN/H₂O^b b the volume ratio of the former to the latter is 3:1;	rt	6	S	94	7.3
2	5b	CH₃CN/H₂O^b b the volume ratio of the former to the latter is 3:1;	rt	6	S	93	5.4
3	5a	THF/H₂O^b b the volume ratio of the former to the latter is 3:1;	rt	6	S	99	1.2
4	5b	THF/H₂O^b b the volume ratio of the former to the latter is 3:1;	rt	6	R	99	4.0
5	5b	CH₃CN^c c no desired product;	rt	48	-	-	-
6	5b	THF	rt	48	R	30	1.6
7	5a	EtOH/H₂O^b b the volume ratio of the former to the latter is 3:1;	rt	6	S	54	7.5
8	5b	EtOH/H₂O^b b the volume ratio of the former to the latter is 3:1;	rt	6	R	63	1.1
9	5a	EtOH	rt	6	S	60	2.3
10	5b	EtOH	rt	6	-	65	0
11	5a	EtOH/H₂O^b b the volume ratio of the former to the latter is 3:1;	-10	24	S	84	0.1
12	5b	EtOH/H₂O^b b the volume ratio of the former to the latter is 3:1;	-10	24	S	89	1.2
13	5a	EtOH/H₂O^b b the volume ratio of the former to the latter is 3:1;	-25	72	-	60	0
14	5b	EtOH/H₂O^b b the volume ratio of the former to the latter is 3:1;	-25	72	-	61	0


entry^a a The reaction was performed with 0.6 mmol aromatic aldehyde and 6 mmol nitromethane in 4 mL solvent (EtOH:H2O, 3:1, v/v);	R	time / h	Configuration	Yield^c c isolated yield; / %	ee^d d enantiomeric excess was determined by HPLC using a Chiracel OD-H column. The absolute configurations of all products were determined by comparing the retention time from HPLC data on the products with those in the literature data.19-21 / %
1	4-CN	36	S	98	2.1
2	4-F	36	S	85	0.2
3	2-NO₂	12	S	87	1.3
4	3-NO₂	16	S	83	1.2
5	3-Cl	24	S	80	2.7
6	4-MeO	48	S	25	1.0
7	4-N(CH₃)₂^b b no reaction;	48	-	-	-
8	2-CH₃	48	S	68	0.5

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[1] *e-mail: zhoujing@tmu.edu.cn; lishaoyong@tmu.edu.cn