4,5,6,7-Tetrahydro-4-oxothionaphthene → 4,5,5a,6-tetrahydro-7H-indeno[5,4-b]thiophen-7-one

Participants

Reaction Steps

6,7-dihydro-1-benzothiophen-4(5H)-one was obtained with an overall yield of 43% via the acylation of thiophene by succinic anhydride followed by reduction of the ketone formed and by the cyclisation of 4-(2-thienyl)butanoic acid in the presence of the laton's reagent. Next, 4,5,5a,6-tetrahydro-7H-indeno[5,4-b]thiophen-7-one was synthesised from 6,7-dihydro-1-benzothiophen-4(5H)-one with an overall yield of 30%. The latter product was further reacted with one equivalent of PhLi in ether followed by acidification of the reaction medium to give a mixture of 7-phenyl-5,5a-dihydro-4H-indeno[5,4-b]thiophene and 7-phenyl-5,8-dihydro-4H-indeno[5,4-b]thiophene as shown in the scheme below

Provenance & Evidence