UNUSUAL CONDENSATION OF 2-(2-DIMETHYLAMINOVINYL)-1-BENZOPYRAN-4-ONE WITH DIMETHYL ACETYLENEDICARBOXYLATE - FORMATION OF 2,3-BIS(METHOXYCARBONYL)XANTHEN-9-ONE
Ck. Ghosh et al., UNUSUAL CONDENSATION OF 2-(2-DIMETHYLAMINOVINYL)-1-BENZOPYRAN-4-ONE WITH DIMETHYL ACETYLENEDICARBOXYLATE - FORMATION OF 2,3-BIS(METHOXYCARBONYL)XANTHEN-9-ONE, Journal of the Chemical Society. Perkin transactions. I, (15), 1997, pp. 2167-2168
Reaction of dienamine 2 (R = H and Me) with N-phenyl-maleimide or chro
mone 3 gives xanthones 5 and 8, respectively, through initial [4 + 2]
cycloaddition, whereas reaction with dimethyl acetylenedicarboxylate a
ffords xanthone 13.