Homoenolate equivalents, Brook rearrangement

Addition of ketone enolates to acyl silanes, followed by Brook rearrangement and closure of the resulting carbanion onto the pendant ketone carbonyl leads to 1,2-cyclopropanediol products such as 67. In the presence of an appropriate electrophile and using a sodium amide base, 67 serves as a homoenolate equivalent, generating y siloxy- hydroxyketone 68 as a mixture of diastereomers whose stereochemistry was not determined. ... 

Homoenolate equivalents (d reagents) are less conunon than nucleophilic acyl equivalents. The uses of 1-trimethylsilylallyl alcohols as effective homoenolate equivalents have been discussed. y-Alkylation of the trimethylsilyloxy-stabil-ized allylic anion formed by Brook rearrangement leads to the (isolable) tri-methylsilylenol ether (18) (Scheme 16). y-Alkylation of the functionalized ally-loxy-carbanion (19) has been reported. ... 

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