A Convenient Multigram Synthesis of Highly Enantioenriched Methyl 3-Silylglycidates
作者:Jason T. Lowe、Willmen Youngsaye、James S. Panek
DOI:10.1021/jo060134g
日期:2006.4.1
A multigram scale synthesis of the four stereoisomers of methyl 3-silylglycidates (epoxysilanes) with high enantiopurity is described. Key reactions include a Sharpless asymmetric epoxidation (SAE) of a trans-vinylsilane and an enzymatic resolution of a racemic cis-epoxysilane to establish the desired configurations. Few chromatographic separations (5 columns out of 13 steps) are required for purification, establishing a convenient reaction sequence for both the trans- and cis-isomers.
Organosilanes in Synthesis: Application to an Enantioselective Synthesis of Methyl-<scp>l</scp>-callipeltose
作者:Hongbing Huang、James S. Panek
DOI:10.1021/ol034582b
日期:2003.5.1
[GRAPHIC]Methyl-L-callipeltose, the carbohydrate associated with callipeltoside A, has been synthesized in eight steps and 23% overall yield from enantioenriched allylsilane 6 and acetaldehyde. The key steps are a highly diastereoselective formal [4 + 2] annulation and a Cr(Vi)-catalyzed oxidative C-C bond cleavage to produce lactone 11.