New Aryl and Vinyl Amination Methods

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DESCRIPTION: (provided by applicant) This proposal describes free radical-mediated aryl and vinyl amination reactions to synthesize indoline and pyrrolidine heterocycles, respectively. By virtue of the pH-neutral conditions involved, this technology is superior to most alternative methods by measures of chemoselectivity. The strategy differs conceptually in that activation of a nitrogen carbon pi bond in the amine is involved instead of nitrogen-hydrogen sigma bond activation. To accomplish amination, carbon radicals are regioselectively added to the nitrogen of the azomethine. In so far as carbon radicals are known to add efficiently to the carbon of a variety of azomethinecontaining functional groups, the additions described are highly nonconventional and nearly without precedent. The mild reaction conditions are uniquely well-suited to transformations of structurally complex and highly functionalized intermediates used in target-oriented synthesis. The use of radical intermediates also allows development of tandem bond-forming processes. The development of radical-mediated aryl amination is extended to convergent indoline annulation strategies. These processes are unique in their ability to enantioselectively construct indoline heterocycles, including alpha-amino acids. To illustrate some of the important characteristics of this method, a total synthesis is proposed of a member of the ambiguine indole alkaloids for which no synthesis route exists. The development of free radical-mediated vinyl amination includes use of the enamine products as intermediates toward functionalized pyrrolidines. The importance of these pyrrolidinyl enamines is demonstrated by the convergent and concise synthesis of nat-mitomycin C for which no enantioselective synthesis currently exists.