Ireland silyl ester enolate rearrangement

The Johnson Ortho Ester Rearrangement 7.22.8 The Ireland Silyl Ester Enolate Rearrangement 722.9 Charge-accelerated Claisen Rearrangements 7.22.10 Cat ysis of Claisen Rearrangements 722.11 Competitive Rearrangements... 

It is important to note, however, that an observed erosion of diastereoselectivity in the Ireland silyl ester enolate rearrangement can be attributed either to the geometric integrity of the silylketene acetals or the selectivity of the chair-like vs. boat-like transition states, and interpretation and improvement of experimental stereoselectivities must take into account both of these factors. 

A related problem is elimination in ester enolates with leaving groups in the -position. Knight and coworkers observed virtually no a-allyl- -amino acid product in the Ireland silyl ester enolate rearrangement of phthalate (213 Scheme 41). Rearrangement of the -methoxycarbonyl analog (214), however, provided methyl ester (215) in a 79 21 mixture of stereoisomers after treatment with etheral diazomethane. 

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