Vasicine from Adhatoda vasica as an organocatalyst for metal-free Henry reaction and reductive heterocyclization of o-nitroacylbenzenes

Abstract Vasicine, a quinazoline alkaloid, from the leaves of Adhatoda vasica , has been utilized as an efficient catalyst for metal and base free Henry reaction of various aldehydes with nitro alkanes. The method can be used in the synthesis of various β-nitro alcohols under mild reaction conditions without use of hazardous organic solvents and expensive catalysts. Vasicine is also applied successfully for one pot synthesis of 2,1-benzisoxazoles from o -nitroacylbenzenes in good yields under mild conditions.