Cyclopropanation of areno-condensed 4H-pyrans with dihalocarbenes

The addition of dihalocarbenes to 1H-benzo[f]chromenes and 4H-chromenes gave a number of dihalotetrahydro(benzo)cyclopropa[b]-chromenes containing donor and acceptor substituents at different positions. It was found that in the case of 1,3-disubstituted 1H-benzo[f]-chromenes, the reaction proceeds diastereoselectively with the formation of trans-isomers. 12H,13H-7a,12a-Methanobenzo[f]indeno-[1,2-b]chromene and 12,13-dihydro-14H-7a,13a-methanodibenzo[a,h]xanthene, representatives of new heterocyclic systems, were obtained.