Uncatalyzed diastereoselective synthesis of alkyliminofurochromone-derived benzylmalononitriles via a three-component cascade reaction: competition between Diels–Alder cycloaddition and Michael addition

Abstract

Diastereoselective Michael addition reactions of 3-(alkylamino)-9H-furo[3,4-b]chromen-9-one intermediate, produced from the [1 + 4] cycloaddition/tautomerization reaction between 3-formylchromones and alkyl isocyanide in dry CH₂Cl₂, with arylidene malononitrile were developed to afford a wide range of functionalized 2-((S)-((R,Z)-3-(alkylimino)-9-oxo-3,9-dihydro-1H-furo[3,4-b]chromen-1-yl)(aryl)methyl)malononitrile derivatives in good yields and excellent diastereoselectivities under mild conditions. Excellent diastereoselectivity has been achieved to yield products containing two stereogenic carbons and one stereogenic imine group. Two C–C and one C–O bonds were selectively formed to provide new alkylated iminofurochromones in good yields.