Methods for the total chemical synthesis of enantiomerically-pure 7-(2'-trimethylsilyl)ethyl camptothecin

Abstract

The present invention discloses and claims five (5) novel, highly efficient synthetic routes for the total synthesis of enantiomerically-pure (i.e., 99%) 7-(2'-trimethylsilyl)ethyl camptothecin (BNP1350; Karenitecin; Cositecan). These aforementioned synthetic schemes are the first to disclose the total syntheses of 7-(2′-trimethylsilyl)ethyl camptothecin using a highly novel direct, non-linear and convergent synthetic strategy which involves annealing the key C7-(trimethylsilyl)ethyl side chain-bearing A ring key synthons to an enantiomerically-pure tricyclic pyridone; rather than through the conventional methodology which incorporates the C7-(trimethylsilyl)ethyl side chain as the final synthetic step on a totally synthesized camptothecin parent compound. The current novel synthetic approaches reported herein since utilize desirably functionalized A-ring with preinstalled trimethyl silyl ethyl side chain, the aforementioned synthetic methodologies have a wider scope of making wide range of pharmaceutically relevant A-ring substituted BNP1350 analogs by substituting desirably functionalized nitro or protected amino phenyl carboxy A-ring as the starting material.