Resumen

PILLI, Ronaldo A.  y  RIATTO, Valéria B.. Stereoselective addition of chiral titanium enolates to 5-substituted five-membered oxocarbenium ions. J. Braz. Chem. Soc. [online]. 2008, vol.19, n.3, pp. 583-599. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532008000300030.

The sterochemical outcome of the addition of chiral titanium enolates to g-lactols derived from (S)-glutamic acid were examined. When 5-substituted g-lactols were treated with chiral titanium enolates of N-acetyl-, N-propionyl-, N-bromoacetyl- and N-phenylacetyl oxazolidin-2-ones, only two diastereoisomers were obtained, revealing complete facial control by the chiral titanium enolate while the oxocarbenium ion facial discrimination was dependent on the nature of the enolate R³ substituent. After desilylation with aqueous HF/CH₃CN, LiBH₄ reduction allowed the efficient preparation of the corresponding trans-2,5-disubstituted tetrahydrofuran diols and recovery of the chiral auxiliary.

Palabras llave : oxocarbenium ions; chiral titanium enolates; trans-2,5-disubstituted tetrahydrofurans.