P. Dallemagne et al., SYNTHESIS OF NEW THIENOCYCLOPENTA[3,2-D]-OXAZOLE AND THIAZOLE DERIVATIVES, Journal of heterocyclic chemistry, 30(3), 1993, pp. 799-802
Synthesis of thieno[2',3':5,4]cyclopenta[3,2-d]oxazole and thiazole de
rivatives are achieved by insertion of carbon dioxide and disulfide in
to chloro-5,6-dihydro-4H-cyclopenta[b]thiophen-6-one.