STTR Phase I: Enzymatic Synthesis of Chiral Cyclopropanes for Pharmaceutical Drug Synthesis and Agricultural Crop Protection Applications

The broader impact/commercial potential of this Small Business Innovation Research Phase I project is to develop novel, breakthrough enzyme-catalyzed reactions that can be applied to the production of pharmaceuticals and crop protection agents. By establishing a broadly applicable biocatalytic alternative to produce an important class of compounds called chiral cyclopropanes, Provivi will create safer, cleaner, and lower cost synthetic routes. In most cases the application of this new biocatalytic reaction will reduce the number of steps and lower the required capital investment for the synthesis of these key building blocks. The new enzyme technology being developed in this research will improve the synthesis of both existing drugs and compounds in current drug development pipelines. Further applications are envisioned in the production of new crop protection agents. The enzymes being developed have the advantage of being optimizable for each specific target product using modern molecular biology methods. Furthermore, performing the reactions in aqueous conditions will reduce the need for organic solvents, improving the sustainablility of the processes. Replacing existing chemical routes with the more efficient and sustainable enzyme-catalyzed steps will reduce the cost and improve the purity of many advanced pharmaceutical intermediates used in drug synthesis. The technical objectives of this Phase I research project are to demonstrate the application of the novel enzymatic cyclopropanation reaction to the production of a variety of commercial drug substances. Chiral cyclopropanes are key substructures found in a number of pharmaceutical and crop protection compounds. The cyclopropane-containing building blocks used in the synthesis of these compounds contain at least one, and often more than one, chiral center. Since biological activity typically requires having a single stereoisomer, chemical methods that achieve high stereoselectivity are continually sought. For cyclopropanation reactions, the existing methods typically rely on transition-metal catalysts such as rhodium bearing chiral ligands. The biocatalytic method offers clear advantages over the contemporary chemistry in that it will circumvent the use of rare, expensive metals and costly auxiliary ligands for these types of reactions. High temperatures and harsh conditions will also be avoided. In this research, high-throughput screening will be used to identify improved variants that catalyze desired cyclopropanation reactions at greater rates and with increased stereoselectivity. By developing an expanded set of cyclopropanation biocatalysts with capabilities to act on a wider range of starting materials, the scope and utility of this novel enzymatic reaction will be increased.