A Pathway of Synthesis Toward the Aspidosperma Alkaloids

Abstract

A recent synthesis of a vincadifformine (1) derivative followed a c-b-a order of bond construction,² which postpones the introduction of the angular ethyl group until a late stage of the reaction sequence. In view of the new, ready access to compounds^3,4 whose structures represent nearly the full complement of carbons characteristic of the non-tryptamine portion of the Aspidosperma alkaloids their use in the total synthesis of such natural bases could be envisaged. The present communication illustrates a c-b-a approach to Aspidosperma alkaloid synthesis by exploitation of the pyran derivative 2 and hence by early introduction of the angular ethyl group.⁵