Rhodium HOMO orbitals

Doyle et al. (39) expanded the rhodium-catalyzed generation of isomiinchnones from diazoacetacetamides and subsequent trapping with dipolarophiles (38). As shown in Scheme 10.12, in the case of diazoacetoacetyl urea (79) the derived isomtinchnone 80 reacts with methyl propiolate to give a 2 1 mixture of cycloadducts 81. The resulting regiochemistry is successfully rationalized using frontier molecular orbital (FMO) theory as being isomiinchnone-HOMO controlled. This result represents one of the few reactions in which the cycloadducts from isomiinchnones and alkynes are stable. 

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