Synthesis Of Optically Active 2-Amino-1 '-Benzyl-2 ',5-Dioxo-5h-Spiro[Indeno[1,2-B]Pyran-4,3 '-Indoline]-3-Carbonitriles Catalyzed By A Bifunctional Squaramide Derived From Quinine

The first organocatalytic asymmetric reaction of propylene malononitrile with oxoindole and 1,3-indandione for the synthesis of chiral indeno-spiro compounds has been developed. Under bifunctional squaramide catalysis, a wide range of optically active 5H-spiro[indeno[1,2-b]pyran-4,3 '-indoline] derivatives were obtained in excellent yields (up to 95%) with moderate to good enantioselectivities (up to 82%). Enantioselectivities of 90-99% were achieved through a simple recrystallization procedure for most products. These indeno-spiro compounds are promising candidates for drug discovery and biochemistry.