SusChEM: The Use of Ti-C Bonds for RNC Insertions and Dynamic Kinetic Resolutions

Columbia University, New York NY

Investigators

Abstract

In this project, funded by the Chemical Structure, Dynamics, & Mechanisms B Program of the National Science Foundation, Professor Jack R. Norton at Columbia University leads a team exploring fundamental issues in organotitanium chemistry. Titanium, inexpensive and nontoxic, offers sustainable ways of carrying out a variety of chemical transformations. This project aims to use inexpensive titanium-based reagents for the synthesis of valuable organic compounds - not only heterocycles but also the enantioenriched compounds essential to the pharmaceutical industry. This project involves a mixture of inorganic, organometallic, and organic chemistry, and is therefore ideal for training young workers for careers in science. Students in the research group are encouraged to interact with both academic and industrial scientists, better preparing themselves for permanent positions on either side of the academic/industrial divide. More specifically, the project addresses three fundamental questions in organotitanium chemistry: (1) The insertion of isonitriles into titanium-carbon (Ti-C) bonds. The insertion of carbon monoxide (CO) into Ti-C bonds has served as a powerful synthetic tool. In principle CO can be replaced by any of the isoelectronic isonitriles (RNC), giving transformations that could be as useful as CO insertion; (2) Dynamic kinetic asymmetric transformations. Chiral titanaaziridines and titanaoxiranes undergo rapid enantiomer interconversion, a property which makes them potentially useful for dynamic kinetic asymmetric transformations. In principle, this approach can generate enantioenriched chemicals from inexpensive racemic starting materials; and (3) Replacement of cyclopentadienyl ligand based Ti reagents with less expensive and more abundant alkoxy ligand based Ti reagents.