PROCESS FOR CONVERTING 2,7-DIHYDROXY-5-ISOPROPYLIDENE-9-SUBSTITUTED-2,6-METHANO-3,4,5,6-TETRAHYDRO-2H-1-BENZOXOCIN TO TRANS-1-HYDROXY-3-SUBSTITUTED-6,6-DIMETHYL-6,6A,7,8,10,10A-HEXAHYDRO-9H-DIBENZO(B,D)PYRAN-9-ONES

摘要

Reaction of an aluminum halide with a 2,7-dihydroxy-5- isopropylidene-9- substituted-2,6-methano-3,4,5,6-tetrahydro -2H-1- benzoxocin in an organic solvent effects cleavage of the pyran ring system with concomitant recyclization to provide exclusively a trans-1- hydroxy-3-substituted-6,6- dimethyl-6,6a,7,8,10,10a-hexahydro-9H-dib enzo b,d!pyran-9-one.