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Reduction of 2-Alkyl-2-carbomethoxycyclopentanone Derivatives with Sodium Borohydride. Part 2. The Elucidation of the Diastereoselective Control.-Four new β-ketoesters (III) are designed and submitted to NaBH4-reduction in polar protic media. The diastereoselective control in this process depends on blockage of the re-face of (III) by a proposed carbonyl-π-stacking type interaction. -(TEIXEIRA, L. H. P.; BARREIRO, E. J.; FRAGA, C. A. M.; Synth.

diastereoselective syntheses, enantioselective syntheses diastereoselective syntheses, enantioselective syntheses (incl. cis/trans-isomerism) O 0031 -047Studies on the Diastereoselective Reduction of 2-Acetyl-2-alkyl-γbutyrolactones with Boron Hydrides.-The diastereoselectivity of borohydride reduction of the title butyrolactones under varying reaction conditions (i.e. presence or absence of chelating agents) is studied in detail.The results indicate that the diastereoselectivity is more dependent on steric interactions than on chelation factors. -(TEIXEIRA, LIS H. P.; DE SOUZA, MARIA CECILIA B. V.; RAMOS, MARIA DA CONCEICAO K. V.; DE AQUINO NETO, FRANCISCO R.; BARREIRO, ELIEZER J.; FRAGA, CARLOS A. M.; Synth. Commun. 32 (2002) 4, 505-526; Lab. Avaliacao Sint. Subst. Bioativas, Fac. Farm., Univ. Fed. Rio de Janeiro,