Transition-Metal-Catalyzed Carbonylative Synthesis and Functionalization of Heterocycles

Abstract

Heterocycles are ubiquitous in natural products, pharmaceuticals, organic materials, and numerous functional molecules. These structural units probably constitute the largest and most varied family of organic compounds. Hence the development of new procedures for heterocycles synthesis has been a hot research topic for over centuries. Among all the new synthetic methods, transition-metal-catalyzed reactions are attractive. Those reactions can formulate complicated heterocycles efficiently from available starting materials under mild conditions and atom economical routes. Among them, transition-metal-catalyzed carbonylation reaction has become an efficient and useful tool in organic synthesis since the first hydroformylation reaction developed by W. Reppe at BASF in the 1930s. Since then impressive progress has been achieved in this area. In nowadays, various types of carbonylation reactions were established. Substrates including aryl halides, olefins, alkynes or simply C-H bond can be activated and produce the corresponding carbonyl-containing compounds smoothly. On the other hand, carbon monoxide was discovered and identified in the 18th century. Since the first applications in industry around 80 years ago, academic and industrial laboratories have explored uses of CO in chemical reactions broadly. However, because of the special physical properties of CO, organic chemists were often reluctant to apply carbonylations frequently in laboratories. Hence, different kinds of CO surrogates were developed and applied in carbonylation reactions, such as metal carbonyl compounds M(CO) x , formates, alcohols, formic acid, aldehyde, biomass and carbon dioxide. Those CO surrogates offer interesting opportunities for carbonylation reactions. This account mainly outlines our progress in the development of transition-metal-catalyzed carbonylative synthesis and functionalization of heterocycles from 2012 to 2018. With copper, palladium, rhodium, ruthenium and iridium as the catalysts and relying on the activation of carbon-halogen and carbon-hydrogen bonds, we are able to synthesis various of heterocycles by using CO gas or CO surrogates as the C1 building blocks.