A Catalyst-Free Cycloaddition Reaction: Access to Spiro[chroman-3,2 '-indene-1 ',3 '-dione] Scaffolds

We have reported herein a catalyst-free cycloaddition of ortho-hydroxyphenyl-substituted para-quinone methides and 2-arylideneindane-1,3-diones by which a series of chromans featuring a spiro indane-1,3-dione scaffolds were obtained in high yields without any additives. Importantly, both anti- and syn- diastereomers could be obtained as single diastereomers respectively. Moverover, the current methold provides a novel and convenient approach for the efficient incorporation of the two biologically important scaffolds (chroman and spiro indane-1,3-dione).