Diastereoselective [3 + 2] cycloaddition of 3-ylideneoxindoles with in situ generated CFHCHN: syntheses of CFH-containing spirooxindoles.

An efficient [3 + 2] cycloaddition of 3-ylideneoxindoles with in situ generated CFHCHN for the syntheses of spirooxindoles has been developed. This methodology gives access to a range of relatively complex spirooxindoles featuring a CFH group and three contiguous stereogenic centers in up to 84% yield and 99 : 1 trans/cis.