Enabling the optimal design of molecular structure for biologic function requires the invention of new methodologies that are chemo-, regio-, diastereo-, and enantio-selective to allow access to the designed molecular target in a time-efficient manner regardless of its structural complexity. Another aspect of importance is to design such methodologies that also are atom economic - ie to maximize the use of valuable raw materials and to minimize the generation of waste. Furthermore, the development of methods that form multiple bonds in a single pot wherein molecular complexity is rapidly assembled offers the opportunity to reduce step count. Multi-bond forming reactions introduce more structural complexity in a single step and thereby shortens step count. Metal catalyzed cycloadditions has the advantage of using the metal and its attendant ligands to control selectivity, notably diastereo- and enantioselectivity. This latter ability of metal complexes to control selectivity provides incredible opportunity uniquely in allylic alkylations because the exact same catalysts are applicable to formation of a wide diversity of bond types - C-H, C-O, C-N, C-F, C-S, C-P, and C-C, etc., and a wide diversity of mechanisms for enantiodiscrimination. The targets have biological activity mainly as anti-cancer and anti-viral agents. Citrinadin A exhibits cytotoxicity against murine leukemia L1210 and human epidermoid carcinoma KB cells. A facile synthesis will confirm stereochemistry and, importantly, supply larger quantities for further biological evaluation. Welwistatin (N-methylwelwitindolinone C isothiocyanate) is a potent MDR reversing agent reducing the IC50 by 90 fold for many anticancer agents. The serine protease inhibitors, the aeruginosins, have potential as antiviral agents. The cyclotryptamine alkaloids exhibit a broad range of biological properties including antitumor, antiviral, antifungal, and analgesic triggering the question of how structural changes may beget selectivity. The hexacyclic ascidian perophoramidines induce apoptosis by PARP cleavage and the more complicated communesins are microfilament disrupters. The aspidosperma type indole alkaloid, kopimaline A reverses multidry resistance in vincristine-resistant KB cells and has not been synthesized previously.
Synthesis of complex potential pharmaceutical candidates made easy is the goal of this research. Designing safe and efficacious pharmaceuticals with minimum side effect profiles requires proper design of molecular structure. Inventing novel synthetic methodologies based upon chemo-, regio-, diastereo-, and enantioselective catalytic processes will enable new concepts in synthetic strategies that will enable drug design.
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