ENANTIOSELECTIVE ARYLATIONS UTILIZING COPPER CATALYSTS AND DIARYLIODONIUM SALTS

Abstract

Diaryliodonium salts are a subclass of hypervalent iodine compounds that can function as pseudo aryl halides in oxidative addition reactions with copper(I) salts to generate copper(III) arene complexes. These copper(III) species may be utilized as intermediates in cross-coupling methods, which render the copper complexes catalytic. Further, the reaction of copper(I) with diaryliodoniums is very facile and operates under mild reaction conditions, thus providing a useful platform to develop highly selective asymmetric arylation methodologies.

Chapter 1 discusses the structure and synthesis of diaryliodonium salts and their reaction with copper. Experimental evidence is presented in support of the oxidative addition mechanism between the hypervalent iodine compounds and copper complexes.

Chapter 2 discusses the development of a copper-catalyzed enantioselective α−arylation reaction between diaryliodonium salts and silyl ketene N,O-acetals. Importantly, the use of a diaryliodonium as a surrogate for an aryl halide in the cross-coupling manifold allows for a mild reaction that does not racemize the sensitive α-aryl carbonyl product.

Chapter 3 discusses the extension of the enantioselective arylation to the use of tryptamide nucleophiles in order to generate C(3)-aryl pyrroloindolines. The tryptamide arylation was applied to the total synthesis of polypyrroloindoline natural products. Specifically, the arylation was used to complete the syntheses of hodgkinsine, hodgkinsine B, and a quadrigemine.