Cram-Felkin stereochemical control

J. I Cram-Felkin and Anti Cram-Felkin Stereochemical Control... 

Achiral allylic silanes and chiral aldehydes. The stereochemical course of reaction for simple allylsilanes is largely governed by Cram (Felkin-Anh) [29] or chelation control [lOh]. Two examples which illustrate this phenomenon are shown in Scheme 10-10 [30]. In the first example, the reaction of 2-phenylpropanal 19 with allyltrimethylsilane 20 affords the homoallylic alcohols 22 and 24 with almost no selectivity. However, methallylsilane 21 afforded a much higher syn selectivity under the influence of BF3-OEt2. The reaction of the n-alkoxy aldehyde... 

The stereochemical outcome of the Mukaiyama reaction can be controlled by the type of Lewis acid used. With bidentate Lewis acids the aldol reaction led to the anti products through a Cram chelate control [366]. Alternatively, the use of a monoden-tate Lewis acid in this reaction led to the syn product through an open Felkin-Anh... 

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