Rhodium-Catalyzed Oxygenative [2 + 2] Cycloaddition of Terminal Alkynes and Imines for the Synthesis of β-Lactams
Insu Kim, Sang Weon Roh, Dong Gil Lee and Chulbom Lee*
*Department of Chemistry, Seoul National University, Seoul 151-747, Republic of Korea, Email: chulbomsnu.ac.kr
I. Kim, S. W. Roh, D. G. Lee, C. Lee, Org. Lett., 2014, 16, 2482-2485.
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Catalytic generation of a ketene species directly from a terminal alkyne in the presence of a Rh(I) catalyst and 4-picoline N-oxide provides a novel and efficient entry to the Staudinger synthesis of β-lactams with high trans diastereoselectivity under mild conditions. Mechanistic studies suggest that the reaction proceeds through a metalloketene rather than free ketene intermediate.
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Staudinger synthesis, β-lactams, N-oxides