Abstract
Spiro[benzo[b]thiophene-2(3H), 1'-cyclopropan]-3-ones (IIIc-1-IIIc-11) and their aza analogs, such as spiro[cyclopropane-1, 2'(3'H)-thieno[3, 2-c]pyridin]-3'-one (IIIc-12) as well as spiro[cyclopropane-1, 2'(3'H)-thieno[2, 3-b]pyridin]-3'-one (IIIc-13), were synthesized from thiosalicylic acids and from 4- and 2-mercaptonicotinic acids, respectiely, in three steps. Decarboxylation of 4', 5'-dihydrospiro[benzo[b]thiophene-2(3H), 3'(2'H)-furan]-2', 3-diones (IIc) gave 2, 3-dihydrobenzo[b]thieno[3, 2-b]furans (IVc) along with the desired spirocyclopropane compounds (IIIc).The ratios of IIIc to IVc were greatly influenced by the substituents on the benzene ring.
