Stereoselective Furan-Iminium Cation Cyclization in the Construction of the Core Structure of Manzamine A

A new type of furan-iminium cation cyclization was developed and used to construct the ABC ring of manzamine A. The cyclization proceeded
at the 2-position with complete regio- and stereoselectivity to give a spiro-center. The product was efficiently converted to the highly substituted
core structure of manzamine A.