Wittig reaction trichlorosilane

More recently, P-cored derivative (116) was prepared from a straightforward combination of a Heck coupling, to afford an intermediate functionalised stil-bene phosphine oxide (114),a Horner-Wittig reaction yielding the phosphine oxide (115), and finally trichlorosilane reduction (Scheme 31) [89]. Using similar strategies, both the valence isoelectronic N- (117) and C- (118) cored dendrimers have been prepared (Scheme 31). 

Reuse of the phosphine resins for Wittig reactions has been reported without details several times. In the only detailed results 92% conversion of phosphine oxide to phosphine with trichlorosilane was attained with a 2% cross-linked polymer, and repeated synthesis of stilbene by quatemization with benzyl bromide and Wittig reaction with benzaldehyde gave 97% gc yields in both the second and the third cycles based on the amount of phosphonium bromide used (H). Identical recycling of a 20% cross-linked macroporous polymer gave 75% gc yield of stilbene compared with 80% from the first use (131. 

A chemoselective Ireland-Claisen rearrangement has been reported by Fujiwara and co-workers. Methyl trichlorosilane was essential for the success of this transformation by suppressing the [2.3]-Wittig rearrangement pathway. The reaction yields 146 as a single diastereomer after esterification. ... 

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