RESUMEN
The first cyclization of para-quinone methide derivatives with alkynes was established by utilizing the [4 + 2] reaction of ortho-hydroxyphenyl-substituted para-quinone methides with ynones or benzyne, which efficiently constructed the scaffolds of chromene and xanthene in high yields (up to 88%). This protocol has not only fulfilled the task of developing cyclization reactions of para-quinone methide derivatives but also provided an efficient method for constructing chromene and xanthene scaffolds.
RESUMEN
The first catalytic asymmetric construction of the tryptanthrin skeleton has been established, taking advantage of a palladium(0)/chiral ligand-catalyzed enantioselective decarboxylative [4 + 2] cyclization of vinyl benzoxazinanones with isatins. This reaction has not only provided a direct and efficient method for constructing chiral tryptanthrin skeleta in high yields and excellent enantioselectivities (up to 97% yield, >99% ee) but also represents the first catalytic asymmetric decarboxylative cyclization of vinyl benzoxazinanones with isatins.