Regio- and stereoselective synthesis of bis-spiropyrazoline-5,3′-chroman(thiochroman)-4-one derivatives via bis-nitrilimines

Regioselective 1,3-dipolar cycloaddition of the bis-nitrilimines with the benzylidene derivatives of chroman-4-one and thiochroman-4-one afforded the corresponding bis-spiropyrazoline derivatives. X-ray analysis was used in the elucidation of the regio- and stereochemistry of the products. Similar reactions of the bis-nitrilimines with 2-benzylidene-3-coumaranone furnished 3,3′-bipyrazole derivatives.