M. Mahmun Hossain

Organic Chemistry
Associate Professor
PhD, University of South Carolina
(414) 229-6698
e-mail: mahmun@uwm.edu
The Hossain Group Page
Selected Publications

The cyclopropyl group is present in a wide variety of naturally occurring compounds and also represents an intermediate for ring opening reactions providing larger ring systems with useful applications. An electrophilic iron carbene, such as 4, has been widely used for the preparation of cyclopropanes. Recently, we have developed a simple and efficient method for synthesizing iron carbene precursors 3 from Cp(CO)2Fe^- 1 and different aldehydes 2 in the presence of chlorotrimethylsilane. The precursors 3 were treated with trimethylsilytriflate in the presence of olefins to generate the cyclopropanes 1. The method has been extended to develop the first asymetric cyclopropanation reactions via iron carbenes having chirality at the carbene ligand and consequently synthesized s(+)-2,2-dimethyl-cyclopropane carboxylic acid 6 used for commercial synthesis of Cilastatin 7, an excellent inhibitor of dehydropeptidase-I that increases in vivo stability of carapenem antibiotic imipenem.

We also are interested in asymmetric organic synthesis catalyzed by chiral metal complexes. More than half of all biologically active molecules are chiral, bearing at least one or more centers of chirality. With the potential advantage of lower dose and greater safety, the synthesis of enantiomerically pure drug is very important. Among the various techniques available to prepare chiral molecules, asymmetric synthesis is the most efficient and economic possibility and in recent years, chiral transition-metal complexes are found to be the most effective to perform asymmetric synthesis with high optical yield. Here, we are working on a project to develop a new air and moisture stable chiral transition-metal Lewis acid and use it to catalyze an asymmetric intramolecular Diels-Alder reaction to synthesize enantiomerically pure bicyclic ring system 8 of (-)Taxol 9, a naturally occurring taxane diterpene with a broad spectrum of potent antileukemic and tumor-inhibiting activity.