Efficient Synthesis of Fluorene Derivatives by Benzannulation of Indene Dienes with Benzoylacetonitrile Catalyzed by Lipase

Abstract

AbstractAn enzymatic method was developed for the synthesis of fluorene derivatives by benzannulation of indene dienes with benzoylacetonitrile in a nonaqueous solvent. Under the optimal reaction condition [indene diene (0.5 mmol), benzoylacetonitrile (0.5 mmol), ethanol (2 mL), lipase from porcine pancreas (5 mg), 50 °C, 24 h], fluorenes bearing various groups were obtained in satisfactory yields (83–93%). This method not only offers a significant advancement in the synthesis of fluorene derivatives, but also represents a new application of lipase in promiscuous enzyme catalysis.