Thermal reactions involving 1-azadienes and allenic esters-(II):(1a) reactions of 3-(N-aryliminomethyl)chromones with allenic esters-tandem reorganization of [2+2] cycloadducts to novel compounds

摘要

Thermal reactions of 3-(N-aryliminomethyl)chromones (4a-d) with ethyl 2,3-butadienoate (5a) and ethyl 4-phenyl-2,3-butadienoate (5b), on refluxing in dry benzene, afford novel compounds 6a-e, apparently, derived from tandem reorganization of initially formed [2+2] cycloadducts. However, reaction of 4a,d with ethyl 2,3-pentadienoate (5c, R = CH3) under similar condition follows a different course yielding novel molecules 7a,d and 8a,d. Plausible mechanistic rationale for the formation of new molecules is proffered. (C) 2015 Elsevier Ltd. All rights reserved.