title: Nonconcerted cycloaddition of 2H-azirines to acylketenes: a route to N-bridgehead heterocycles.
abstract: Reactions of acylketenes, generated from diazo diketones, with 2-unsubstituted and 2-monosubstituted 3-aryl-2H-azirines lead to 1:1 or 2:1 adducts, which are derivatives of 5-oxa-1-azabicyclo[4.1.0]hept-3-ene or 5,7-dioxa-1-azabicyclo[4.4.1]undeca-3,8-diene. According to DFT B3LYP/6-31G(d) computations, the formation of (4+2)-monoadducts proceeds via a stepwise non-pericyclic mechanism. Reaction with methanol transforms quantitatively both 1:1 and 2:1 adducts into 1,4-oxazepine derivatives.
authors: Department of Chemistry, Saint-Petersburg State University, 198504 St. Petersburg, Russia. alexander.khlebnikov@pobox.spbu.ru
authors: Alexander F
authors: AF
authors: Khlebnikov
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authors: Dmitry S
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