Metal-Catalyzed Cross Coupling with N,O-Acetals and Acetals

Princeton University, Princeton NJ

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Abstract

DESCRIPTION (provided by applicant): Among the most ubiquitous scaffolds in medicinal chemistry, biological chemistry, and glycobiology are ?-substituted amines and ethers. The goal of the proposed research program is to define a general and modular catalytic strategy that enables the enantioselective synthesis of these structural motifs, including those imbedded within heterocyclic frameworks, in much the same way that cross coupling serves as an all-purpose and powerful protocol for the assembly of Csp2-Csp2 bonds. To achieve this goal, we will exploit the ability of low-valent transition metal catalysts to undergo oxidative addition to iminium and oxocarbenium ions and show that this underutilized activation mode offers a versatile entry to alkyl cross-coupling reactions. In this contribution, we will pursue catalyst design and development for enantioselective arylation, heteroarylation, and alkylation of readily available and stable N,O-acetals and acetals using organoboronate and organozinc reagents (Specific Aim 1). The substituted dihydroquinolines, piperidines, chromenes, and pyrans that we will obtain from these studies constitute the core structural elements of small molecules that exhibit an array of pharmacological activities. In Specific Aim 2, we will develop a new class of stable Ni precatalyst that is easily activated to Ni(0) and enables more efficient and convenient Suzuki-Miyaura cross-coupling reactions. Reaction development will also demonstrate that the iminium/oxocarbenium ion activation mode facilitates unprecedented bond constructions with simple feedstock chemicals such as electron-deficient olefins and carbon dioxide for the synthesis of allylic ethers, allylic amines, and ?-amino acids (Specific Aim 3).