Stereodivergent Approach to the Avermectins Based on “Super Silyl” Directed Aldol Reactions
作者:Patrick B. Brady、Susumu Oda、Hisashi Yamamoto
DOI:10.1021/ol501327g
日期:2014.8.1
A stereodivergent approach to the spiroketal fragment of the avermectins is described. The strategy utilizes a sequence of three aldol reactions directed by the tris(trimethylsilyl)silyl “super silyl” group. Central to this strategy is that each aldol reaction can be controlled to allow access to either diastereomer in high stereoselectivity, thereby affording 16 stereoisomers along the same linear
Controlling stereochemistry in polyketide synthesis: 1,3- vs. 1,2-asymmetric induction in methyl ketone aldol additions to β-super siloxy aldehydes
作者:Patrick B. Brady、Brian J. Albert、Matsujiro Akakura、Hisashi Yamamoto
DOI:10.1039/c3sc51183a
日期:——
The aldol addition of methyl ketones to β-siloxy and α-methyl β-siloxy aldehydes is described. Careful control of mechanistically distinct aldol reactions leverages 1,2- and 1,3-asymmetric induction, selectively forming syn and anti aldol adducts with excellent diastereocontrol. Experimental and theoretical investigations have provided insight to the factors governing diastereoselectivity.