Carbon-carbon bond formation by nucleophilic addition to imines

Abstract

Barbier-type allylation of unactivated aldimines with allyl bromides in the presence of indium powder took place rapidly in alcoholic solvents, most notably methanol, to give homoallylic amines in good yields. Among a variety of chiral amines tested as auxiliary for asymmetric allylation of aldimines, (R)-phenylglycinol gave the best yield and diastereoselectivity. The configuration of the stereogenic center in the homoallylic amine was determined by oxidative removal of the chiral auxiliary with Pb(OAc)₄ followed by treatment with hydroxylamine hydrochloride. The absolute configuration was determined by comparing the chemical shift from ¹H-NMR spectra of the diastercomeric amides resulted from coupling of the homoallyl amine with Boc-(R)-phenylglycine and Boc-(S)phenylglycine respectively.