SYNTHESIS OF β-VINYL-SUBSTITUTED 4<i>Н</i>-CHROMENES AND [4+2] CYCLOADDITION REACTIONS INVOLVING THEM
DOI:
https://doi.org/10.1007/7256Keywords:
acetylenedicarboxylic acid dimethyl ester, benzo[a]xanthenes, β-formyl-4Н-chromenes, ninhydrin, spiro-substituted 3, 10a-dihydro-2H, 5H-pyrano[2, 3-b]chromenes, 2-vinyl-1H-benzo[f]chromenes, Diels–Alder reaction, Wittig reaction.Abstract
β-Vinyl-substituted chromenes were obtained from 1H-benzo[f]chromene-2-carbaldehydes and 6-bromo-4H-chromene-3-carbaldehyde by the Wittig reaction. The Diels–Alder reaction of the β-vinyl-substituted chromenes with dimethyl acetylenedicarboxylate, ninhydrin, and diethyl 2,3-dicyanofumarate yielded spiro-substituted 3,10a-dihydro-2H,5H-pyrano[2,3-b]chromenes, derivatives of 7a,10-dihydro-12H-benzo[a]xanthene and 7a,8,10,12-tetrahydro-9H-benzo[a]xanthene.
