Conjugatively Stabilized Bridgehead Olefins: Formation and Reaction of Remarkably Stable Homoadamant-3-enes Substituted with Phenyl and Methoxycarbonyl Groups
Conjugatively stabilized double bonds were formed at the bridgehead of homoadamantane by way of the 1,2-carbon shift of adamantylcarbene (-carbenoid) intermediates generated from decomposition of the diazo precursors (1-adamantyl)diazophenylmethane (7) and methyl (1-adamantyl)diazoacetate (10). Decomposition to 4-phenyl- and 4-methoxycarbonyl-substituted homoadamant-3-enes 1 and 2 was much more efficient
Although diazoalkanes are important carbene precursors in organic synthesis, a comprehensive mechanism of photochemical for-mation of carbenes from diazoalkanes has not been proposed. Synergy of experiments and computations demonstrates the in-volvement of higher excited singlet states in the photochemistry of diazoalkanes. In all investigated diazoalkanes, excitation to S1 results in nonreactive internal