Acylation and alkylation reactions. Part V. Some syntheses of tricyclic derivatives of benzo[b]furan-3(2H)-one

Abstract

The synthesis of 5,6,7,8-tetrahydronaphtho[2,3-b]furan-3(2H)-one (2; n= 4), 6,7,8,9-tetrahydro-5H-cyclohepta[4,5]benzo[1,2-b]furan-3(2H)-one (2; n= 5), and 7,8,9,10-tetrahydro-6H-cyclohepta[3,4]benzo[1,2-b]-furan-1 (2H)-one (3; n= 5) is described. Selective hydrolysis, selective transesterification, and selective esterification of the intermediate 1,3-dicarboxy-derivatives of 5,6,7,8-tetrahydro-2-naphthol and its homologues occur. The Dieckmann reaction on ethyl 1,3-diethoxycarbonyl-5,6,7,8-tetrahydro-2-naphthyloxyacetate and 1,3-diethoxycarbonyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yloxyaceate (20; n= 4 and 5) gives the angular hydroxy-esters (22; n= 4 and 5).