Functionalization of alpha- and beta-Amino C-H Bonds Using Cooperative Catalysis

Abstract

Cooperative catalysis has been developed for transformations where at least two reactants are activated in situ by acid or base sensitive catalysts to form the reactive species and subsequent bond formation leads to desired product. This thesis focuses on the development of ɑ-amino C-H alkynylation and β-amino C-H deuteration through the use of cooperative catalysts. In the alkynylation reaction, N-alkylamines and trimethylsilyl substituted alkynes were used to synthesize propargylamines by the cooperative actions of Lewis acid catalysts, B(C₆F₅)₃ and copper complex. The reaction between in situ generated iminium ion and copper alkyne complex afforded the product. The method is applicable to the late-stage functionalization of bioactive amine drug molecules and has been shown to tolerate different functional groups on trimethylsilyl-substituted alkynes. In addition, an enantioselective and diastereoselective version of the method was also developed through the use of chiral copper complex. In the second part, selective deuteration of β-amino C-H bonds of various acylic and cyclic alkyl amines will be introduced. B(C₆F₅)₃ and Brønsted base work cooperatively to afford enamine and deuterated ammonium ion as reactive intermediate. Deuteration of enamine at the β-position and hydride reduction at the ɑ-position gave the selectively deuterated products. Acetone-d₆ was the found to be the optimal source of deuterium. This method was able to incorporate deuterium atoms up to 99% and can be applied in a gram scale reaction without compromising the yield or d-incorporation level.