Enantioselective construction of dihydropyran-fused indoles through chiral calcium phosphate catalyzed oxo-hetero-Diels-Alder reactions by using 2-oxoindolin-3-ylidenes as heterodienes.

ABSTRACT

Carbon-carbon bond formation A highly efficient method for the oxo-hetero-Diels-Alder reaction of 2-oxoindolin-3-ylidenes based on chiral calcium phosphate is described. In general, adducts were obtained with high yields and excellent diastereo- and enantioselectivities (up to 96 % yield, >991 endo/exo, >99 % ee; see scheme, Boc = tert-butoxycarbonyl).