Lewis acid mediated diastereoselective allylation of camphorpyrazolidinone derived α-ketoamides

Diastereoselective allylation of camphorpyrazolidinone derived α-ketoamides was examined using allyltributyltin in the presence of various Lewis acids. The corresponding optically enriched quarternary α-hydroxy carbonyls were obtained in reasonable to excellent material yields (51–95%) and with practical levels of stereoselectivity (up to >95% de) when a stoichiometric amount of Sn(OTf)2 was used. The stereochemical induction is discussed.