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Benzopyrans. Part 41.1 Reactions of 2-(2-dimethylaminovinyl)-lbenzopyran-4-ones with various dienophiles
C K GHOSH, S BHATTACHARYYA, C GHOSH, A PATRA
Published in Royal Society of Chemistry
1999
   
Issue: 20
Pages: 3005 - 3013
Abstract
Dienamine 1 with W-phenylmaleimide and chromenone 14 as well as 15 produces, through initial [4 + 2]cycloaddition, xanthenones 10 and 18, respectively. Initial Michael addition of 1 to chromenones 14 and 16, and dimethyl acetylenedicarboxylate (DMAD), triggers the formation of xanthenone 19, 4-azaxanthenone 26 and substituted fumarate 49, respectively. Initial [2 + 2]cycloadducts of dienamines 1-3 with electrophilic acetylenes always undergo further transformations. Thus, 1 with DMAD, dibenzoylacetylene and ethyl propiolate (EP) ultimately gives xanthenones 33, 34 and 37, respectively, the latter being admixed with flavone 43. Enamine 2, cyclisable to xanthenone 11, gives 33 and 35 with DMAD, and 37 and 44 with EP. Reaction of 3 with DMAD affords 36 exclusively. © The Royal Society of Chemistry 1999.
About the journal
JournalData powered by TypesetJournal of the Chemical Society - Perkin Transactions 1
PublisherData powered by TypesetRoyal Society of Chemistry
ISSN0300-922X