The Formation of Two Kinds of Thiophene Derivatives by the Reaction of the 4<i>H</i>-Pyran-4-thione Derivative with Dimethyloxosulfonium Methylide in a One-pot Process
The reaction of 2,6-dimethyl-3,5-diphenyl-4H-pyran-4-thione with dimethyloxosulfoniummethylide occurred facilely to give two kinds of 2-thienylacetones, accompanied by a five-membered α,β-unsaturated thione, a naphtho-[2,1-b]thiophene derivative, and a hemithioacetal.
2-Acylcyclopent-3-en-1-ol derivatives, 2, were synthesized by the reaction of homopyrones with phenyllithium. The intermediate may be a cyclopropylmethanol derivative, 3, which was isomerized into 2. Similar treatment with methyllithium, methylmagnesiumiodide, or lithium aluminium hydride also gave 2.
monocyclopropanation of 4-pyrones with dimethyloxosulfonium methylide, using a dimethyl sulfoxide hexamethylphosphorictriamide medium in place of neat dimethyl sulfoxide, gave homo-4-pyrone derivatives, which were then rearranged into the 2-furylacetone derivatives, along with hydra ted triketones or the dehydrated naphtho[2,1-b]furan derivative, by means of strong acid catalysis at room temperature.