Journal of Organic Chemistry 2012-07-20

Diastereoselective [4 + 1] cycloaddition of alkenyl propargyl acetates with CO catalyzed by [RhCl(CO)2]2.

Wei Chen, Jia-Hui Tay, Xiao-Qi Yu, Lin Pu

Index: J. Org. Chem. 77(14) , 6215-22, (2012)

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Abstract

A class of alkenyl propargyl acetates, RCH(OAc)C≡CC(CH(3))═CH(2) (5), are found to undergo [4 + 1] cycloaddition with CO (1 atm) in the presence of [RhCl(CO)(2)](2) in refluxing 1,2-dichloroethane to give cyclopentenones (6) in good yields. It has been demonstrated that, when the R group of 5 is a phenyl group bearing o-electron-withdrawing substituents, up to 10:1 diastereoselectivity and 96% yield can be achieved for the [4 + 1] cycloaddition. This process provides a convenient method to construct highly functionalized cyclopentenones that are useful in organic synthesis.