Metal Salt Catalyzed Carbenoid-XIII. On The Mechanisms Of Cyclopropanation And Allylic CH Insertions By Diazo Esters In The Presence Of Olefins And Homogeneous Copper Catalysts
Evidence is presented demonstrating the existence of two paths to the title processes which arise from a common intermediate. A rationale involving catalyzed addition of the diazo compound to the olefin and carbenoid addition to the olefin is proposed. The penultimate intermediate has one new CC bond formed. It is partitioned between products by forming the second CC bond or formation of a hydrocarbenoid allyl complex which collapses to the allylic CH insertion products. Cyclopropanation occurs stereospecifically. The proposed mechanism accounts for the stereospecificity of cyclopropanation, the variance of syn/anti ratios with catalyst concentration when diazoacetic ester is employed and optical inductions with chiral catalysts. The question of whether the alleged carbenoid and/or the penultimate intermediate contain N2 is not answered although it is felt that a cupro-cyclobutane intermediate is the most probable intermediate before product partitioning. © 1976.
D. S. Wulfman et al., "Metal Salt Catalyzed Carbenoid-XIII. On The Mechanisms Of Cyclopropanation And Allylic CH Insertions By Diazo Esters In The Presence Of Olefins And Homogeneous Copper Catalysts," Tetrahedron, vol. 32, no. 11, pp. 1241 - 1249, Elsevier, Jan 1976.
The definitive version is available at https://doi.org/10.1016/0040-4020(76)80078-6
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01 Jan 1976