Reaction of Donor-Acceptor Cyclobutanes with Indoles: A General Protocol for the Formal Total Synthesis of (+/-)-Strychnine and the Total Synthesis of (+/-)-Akuammicine

摘要

A ligand-promoted catalytic 4+2 annulation reaction using indole derivatives and donor-acceptor (D-A) cyclobutanes is reported, thus providing an efficient and atom-economical access to versatile cyclohexa-fused indolines with excellent levels of diastereoselectivity and a broad substrate scope. In the presence of a chiral SaBOX ligand, excellent enantioselectivity was realized with up to 94 ee. This novel synthetic method is applied as a general protocol for the total synthesis of (+/-)-akuammicine and the formal total synthesis of (+/-)-strychnine from the same common-core scaffold.