Cyclopentadienone Synthesis by Rhodium(I)-Catalyzed [3 + 2] Cycloaddition Reactions of Cyclopropenones and Alkynes

J. Am. Chem. Soc., 128 (46), 14814 -14815, 2006. 10.1021/ja065868p S0002-7863(06)05868-9
Web Release Date: October 27, 2006

Cyclopentadienone Synthesis by Rhodium(I)-Catalyzed [3 + 2] Cycloaddition Reactions of Cyclopropenones and Alkynes

Paul A. Wender,* Thomas J. Paxton, and Travis J. Williams

Departments of Chemistry and of Molecular Pharmacology, Stanford University, Stanford, California 94305-5080

email: wenderp@stanford.edu

Received August 12, 2006

Abstract:

The Rh(I)-catalyzed [3 + 2] cycloaddition of cyclopropenones and alkynes is found to provide a highly efficient and regiocontrolled route to cyclopentadienones (CPDs), building blocks of widespread use in the synthesis of natural and non-natural products, therapeutic leads, polymers, dendrimers, devices, and antigen presenting scaffolds. The versatility of the method is explored with 23 examples representing a wide range of alkyne variations (arylalkyl-, dialkyl-, heteroarylalkyl-) and diaryl- as well as arylalkylcyclopropenones. The reactions often proceed in high yield using minimal catalyst loadings and in all cases examined proceed with high or complete regioselectivity. The reaction is readily scalable to produce gram quantities of cycloadduct and provides a unique and versatile route to CPDs that would be otherwise difficult to obtain.

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