Regioselective synthesis of [4b, 12c-cis]-#DELTA#~6a,12b -4b,5,12c,13-tetrahydropyrano-[2,3-c : 4,5-c']bis[1]benzopyran-7-one

摘要

Hitherto unreported [4b,13c-cis]-#DELTA#~6a,12b -4b,5,12c,13-tetrahydropyrano[2,3-c : 4,5-c']bis[1]benzopyran-7-ones 2a-f have been regioselectively synthesized in 65-75% yields from 1-aryloxymethylpyrano[2,3-c][1]benzopyran-5(3H)-ones 1a-f by heaing in N,N-diethylaniline via tandem cyclization involving[3,3] sigmatropic rearrangement followed by enolisation and an internal [1,6] Michael addition of the phenolic moiety to the diene-lactone moiety.