A DIRECTED METALATION ROUTE TO THE ZWITTERIONIC INDOLE ALKALOIDS. SYNTHESIS OF SEMPERVIRINE

Article abstract of DOI:10.1016/S0040-4020(01)85951-2

A synthesis protocol involving beta-lithiation of 2-(2-pyridinyl)indoles(4<*>5) and subsequent reaction with bromoacetaldehyde leads to the indolo<2,3-a>quinolizine (1) ring system.Application of this methodology to 2-(2-pyridinyl)indole 17, which is prepared via Taylor-Boger triazine Diels-Alder annulation chemistry, affords the zwitterionic indole alkaloid sempervirine (3).