The Synthesis of 2-Phenyl-3-nitro-3,4-dihydro-2H-1-benzopyrans

Abstract

A series of 3-nitrochranans, including a 3-phenyl-2-nitrodihydronaphtho[2,1-blpyran, were synthesized in gwd yields by selective reduction of the corresponding 3-nitrochrnenes using sodiun brohydride in methanolic tetrahydrofuran.Altho* the syntheses1-5 and biological activity6 of 3-nitrochromenes h a w attracted significant attention in recent years, the mrresponding saturated analogs, the 3-nitrochromans, have virtually been [e-mail] is, in part, due to the fact that conventional techniques for the preparation of chrdnans from the corresponding chrmenesg .lo,using catalytic hydrogenation or hydride reduction, always resulted in the formation of chramanaminess ~'l,'~.Consequently.