Intramolecular Diels−Alder Reaction of <i>N</i>-Alkyl-2-cyano-1-azadienes: A Study of the Eschenmoser Cycloreversion of Dihydrooxazines as a Route to <i>N</i>-Alkyl-2-cyano-1-azadienes
作者:Irina A. Motorina、Frank W. Fowler、David S. Grierson
DOI:10.1021/jo9614046
日期:1997.4.1
In connection with the development of the intramolecular Diels-Alderreaction (IMDA) of 1-azadienes, the 5,6-dihydro-4H-1,2-oxazine 12has been evaluated as a synthon equivalent of the 2-cyano-1-azadiene system. It was found that the dihydrooxazonium salt 27, generated in situ from the cyclic hydroxamic acid derivative 26, is converted directly to azadiene 4a via tautomerization to the corresponding