Stereoselective synthesis of spirooxindole derivatives using an organocatalyzed tandem Michael Michael reaction.
A highly efficient stereoselective method for the synthesis of functionalized spirooxindole derivatives with three stereogenic centers was realized through an organocatalytic tandem Michael Michael reaction. By employing (S) a,a diphenylprolinol trimethylsilyl ether as the catalyst and N,N' bis[3,5 bis(trifluoromethyl)phenyl]thiourea as the cocatalyst, the reaction between N tritylisatylidenemalononitriles and (E) 7 alkyl 7 oxohept 5 enals yields the desired spirooxindole products in good yields (76 95% and with excellent diastereoselectivities (up to 97 3 dr) and enantioselectivities (up to 98% ee) which can be stereoselectively converted into the spiro[indoline 3,8' isoquinoline] derivative through an intramolecular reductive amination reaction.
Organic biomolecular chemistry