An unexpected acid-catalyzed rearrangement of diacetoxy benzylidenespirostanes to spirochromene acetals and spiroindenes with radical scavenger activity

Abstract

23E-diacetoxybenzylidenespirostanes underwent rearrangement when treated with HCl in CH2Cl2/CH3OH. The course of the rearrangement depends on the substitution pattern in the phenyl ring. While compounds bearing an acetoxy group at the ortho position produced spirochromenes, the partners with no substituent at the ortho position led to spiroindenes. All the rearranged compounds exhibited moderate antioxidant activity.