Boron aldol additions with erythrulose derivatives: Dependence of stereoselectivity on the type of protecting group

Article abstract of DOI:10.1016/S0040-4039(99)01380-5

Boron aldol additions of 1-O-silylated 3,4-di-O-benzyl- and 3,4-di-O-benzoyl-L-erythrulose and achiral aldehydes using dicyclohexylboron chloride have been investigated. The dibenzyl derivative gave syn/syn stereoisomers with high stereoselectivity, whereas the dibenzoyl derivative gave syn/anti stereoisomers. It is believed that, while the dibenzoyl erythrulose gives rise to the E enolate in the presence of dicyclohexylboron chloride, as usually observed with this reagent, only the Z enolate is formed in the case of the dibenzyl derivative.