Homogeneous Gold Catalysis for Regioselective Carbocyclization of Alkynyl Precursors.

ABSTRACT

π-Activation of alkynyl precursors possessing an endogenous carbon nucleophile is one of the imperative topics in homogeneous gold catalysis as it offers Csp3 -Csp2 and Csp2 -Csp2 linked carbocycles. However, the exo-dig and endo-dig cyclization modes unlocks the possibility of both small and large rings respectively, thereby losing regioselectivity. Nevertheless, several gold-catalyzed carbocyclizations which permits one isomer by controlling or avoiding the formation of other went largely unnoticed. Hence, this review is an attempt to summarize such approaches reported from early 2000's to till date along with our viewpoint on contributing parameters for regioselectivity. This review covers only unimolecular reactions with classifications primarily based on the type of endogenous nucleophiles such as silyloxyenols, enamides/enamines, benzenoids, heteroaromatics and alkyls/alkenyls. From an application perspective, these reactions are significant in total synthesis and materials science. Therefore, those reactions that finds application in natural product synthesis and π-functional materials are highlighted in appropriate places.