A cobalt porphyrin efficiently catalyzed the formal [3+2] cycloaddition of alkyl-/aryl-substituted cyclopropanes and carbonylcompounds such as aldehydes and ketones to afford the corresponding substituted tetrahydrofurans. The use of the cobalt porphyrin complex as a Lewis acid to catalyze the reaction via the electrophilic activation of cyclopropanes was demonstrated. The high functional-group tolerance
Scope and Mechanism for Lewis Acid-Catalyzed Cycloadditions of Aldehydes and Donor−Acceptor Cyclopropanes: Evidence for a Stereospecific Intimate Ion Pair Pathway
作者:Patrick D. Pohlhaus、Shanina D. Sanders、Andrew T. Parsons、Wei Li、Jeffrey S. Johnson
DOI:10.1021/ja8015928
日期:2008.7.1
In this work, the one-step diastereoselective synthesis of cis-2,5-disubstituted tetrahydrofuransviaLewis acid catalyzed [3 + 2] cycloadditions of donor-acceptor (D-A) cyclopropanes and aldehydes is described. The scope and limitations with respect to both reaction partners are provided. A detailed examination of the mechanism has been performed, including stereochemical analysis and electronic profiling