Steric Control of Reactive Transition Meal Species

点击翻译按钮获取中文摘要

Transition-metal-catalyzed cycloaddition reactions have clearly been demonstrated to be a powerful tool in organic synthesis. A variety of ring systems can be constructed via transition metal-catalyzed cycloaddition reactions. If one uses carbon monoxide (CO) as one carbon unit, one can expect to get carbocyclic or heterocyclic carbonyl compounds from simple acyclic building blocks. The purpose of the present study was the development of new type of carbonylative cycloaddition reactions using aldehyde (or ketone) π-bond as two-atom unit.Several new types of carbonylative cycloaddition reactions, as shown below was found. In all cases, Ru_3(CO)_<12> was a catalyst of choice. (1) intramolecular [2+2+1]cycloaddition of aldehydes, alkynes, and CO; (2) [4+1]cycloaddition of α,β-unsaturated imines and CO; (3) intermolecular [2+2+1]cycloaddition of ketones (aldehydes), alkenes (alkynes), and CO.In the reaction 3, simple aldehydes (or ketones) did not serve as the substrate, however a wide variety of ketones, such as α-dicarbonyl compounds and N-heterocyclic ketones, can be used in this cycloaddition. A high diastereoselectivity was observed when pyridylmethyl ketone was used as the substrate and cyclopentene was used as an olefin component.