Rearrangement of α-hydroxy imines to α-amino ketones: Mechanistic aspects and synthetic applications

Abstract

In refluxing diglyme, rearrangement of α-hydroxy imines bearing diversely substituted allyl groups or a 3-trimethylsilylpropargyl group on the α-carbon to the nitrogen afforded in good yields α-amino ketones. Migration of allyl or 3-trimethylsilylallyl groups occured without allylic transposition in contrast to the 1-methylallyl group. In the 3 cases studied, the rearrangement of enantioenriched α-hydroxy imines took place with complete 1,2-chirality transfer. The rearrangement was applied to the preparation of (+)-1-benzyl-1-azaspiro[5.5]undecan-7-one, a precursor in the synthesis of (−)-perhydrohistrionicotoxin.