The primary objective of this research program is to develop new synthetic methodology based upon reactions of electron deficient imines and iminium complexes. The scope and general utility of this chemistry will be explored and ultimately applied in the context of natural product total synthesis. Emphasis will be placed upon producing synthetic methods with potentially broad applicability which will be of practical value to chemists involved in synthesis of cancer chemotherapeutic agents. Target molecules include the Ergot alkaloids lysergic acid and lysergol, which will be synthesized via a concise route utilizing an N-tosyl imine/olefin cyclization as a key step. in addition, a total synthesis of the antitumor Amaryllidaceae alkaloid narciclasine will be completed utilizing a novel vinyl silane/N-sulfonyliminium ion cyclization in a pivotal step. A unique pericyclic imino ene reaction of an allenyl silane, which was discovered in the course of a synthesis of the unusual marine alkaloid papuamine, will be explored further and utilized in an approach to the 5,11-methanomorphanthridine class of Amaryllidaceae alkaloids. A reaction of an N-tosyl aldimine with a beta-hydroxyaldehyde to produce a 2,3- dihydro-(6H)-1,3-oxazine, which was discovered in the last grant period, will be explouted in a stereocontrolled approach to 1,3-amino alcohols. The methodology will be applied to preparation of the dihydroxyamino acid moiety of the anticytotoxic natural products, the calyculins.
Showing the most recent 10 out of 15 publications
