Palladium-catalyzed asymmetric [4+2] annulation of vinyl benzoxazinanones with pyrazolone 4,5-diones to access spirobenzoxazine frameworks

Herein, a palladium-catalyzed general synthetic strategy to access an attractive and decorated set of chiral spiro derivatives of benzoxazine compounds is unveiled utilizing vinyl benzoxazinanones reacted with pyrazolone 4,5-diones, which extends the application of vinyl benzoxazinanones with ketones. This asymmetric catalytic [4+2] cycloaddition reaction demonstrates a broad substrate scope with functional group tolerance in yields of up to 76% and up to 96% ee. A facile scale-up and straightforward conversion to diversely substituted products verify the synthetic utility of this method.

Automated summary

Here, a palladium-catalyzed strategy is developed for the synthesis of a diverse set of chiral spiro derivatives of benzoxazine compounds by reacting vinyl benzoxazinanones with pyrazolone 4,5-diones. This method extends the application of vinyl benzoxazinanones with ketones and demonstrates broad substrate scope and functional group tolerance, with yields up to 76% and enantioselectivity up to 96% ee. The facile scale-up and conversion to diversified products confirm the synthetic utility of this approach.