Zr(Ot‐Bu)₄‐Catalyzed Tishchenko Reduction of β‐Hydroxy Ketones.

Abstract

Reduction O 0220Zr(Ot-Bu) 4 -Catalyzed Tishchenko Reduction of β-Hydroxy Ketones. -Zr(Ot-Bu)4 is used as an effective catalyst for the Tishchenko reduction of β-hydroxy ketones to afford 1,3-anti-diol monoesters. Treatment of (IV) with isobutyraldehyde results in formation of a mixture of Tishchenko products; the ratio depends on the reaction temperature. For the anti-aldol educt (VII), a ratio of nearly 1:1 is observed due to epimerization. -(SCHNEIDER*, C.; KLAPA, K.; HANSCH, M.; Synlett 2005, 1, 91-94; Inst. Org. Chem., Univ. Leipzig, D-04103 Leipzig, Germany; Eng.) -S. Adam 22-048

Asymmetric Synthesis of Naturally Occuring Spiroketals

“…Epoxide 378 is treated with lithiated dithiane 377 to give alcohol 379 , which upon hydrolysis with aqueous MeI affords hydroxyketone 380 . Reduction of ketone 380 using Schneider’s conditions at –78 o C gives desired anti ester 381 with good stereoselectivity (98:2) [ 149 ]. Ester 381 is converted to diol 375 after protection and deprotection sequence ( Scheme 83 ).…”