On the Rearrangement of an Azaspiroindolenine to a Precursor to Phalarine: Mechanistic Insights

摘要

In an agronomy-centered investigation directed at the suitability of Phalaris coerulescens (blue canary grass) for introduction into Australia, Colegate and co-workers isolated a furanobisindole alkaloid which they termed phalarine.[1] On the basis of spectroscopic analysis, in particular NMR and MS, the structure of phalarine was assigned as 1 (Scheme 1). This representation was not supported by systematic degradation, let alone corroboratory crystallographic studies. Given our long term involvement in novel indole alkaloids,[2] we took an interest in the structure 1 proposed for phalarine, and began to formulate possible routes for its total synthesis.