Asymmetric Aza‐Morita–Baylis–Hillman Reactions of Alkyl Vinyl Ketones with N‐Protected Imines or In Situ Generated N‐Protected Imines

Abstract

AbstractDABCO‐catalyzed aza‐MBH reactions of N‐Boc imines with MVK and EVK have been thoroughly investigated in the paper. The asymmetric version of this aza‐MBH reaction was also systematically investigated by using a chiral amine or a chiral phosphane catalyst. It was found that most of the N‐protected imines are suitable substrates under the mild reaction conditions and are able to give the corresponding adducts in moderate yields with high ee values. The TQO‐ or LB1‐catalyzed aza‐MBH reactions of N‐protected α‐amidoalkyl phenyl sulfones or α‐amidoalkyl p‐tolyl sulfones with MVK could be well conducted, which provides a facile and direct route to obtain highly enantioselective aza‐MBH adducts. The Boc protecting group of the aza‐MBH product could be easily removed under acidic conditions to give the corresponding α‐methylene‐β‐amino ketone or α‐methylene‐β‐amino alcohol derivatives in good yields.