Description:
<jats:title>Abstract</jats:title>
<jats:p>The reaction of 2,2-dimethylthiirane (4) with diethyl malonate (5) in the presence of sodium ethoxide gave 3-ethoxycarbonyl-5,5-dimethyl-dihydro-2(3H)-thiophenone (6) and a polymer. The yield of 6 could be increased to 65%. The reaction of thiirane, 2-methylthiirane, 2-butylthiirane, 2-hexylthiirane, 1,2-epithiocyclohexane, and 2-phenylthiirane with 5 also gave corresponding dihydro-2(3H)-thiophenone derivatives. Although the reaction of an alkyl-substituted thiirane with 5 selectively gave a product formed by an attack of a carbanion at the less-hindered carbon of the thiirane ring, the major product of the reaction of 2-phenylthiirane with 5 was an isomer formed by an attack at the more hindered carbon of the thiirane ring. The reaction of 4 with ethyl acetoacetate gave 3-acetyl-5,5-dimethyl-dihydro-2(3H)-thiophenone selectively. A product 6 was also obtained by a reaction of 4 with 5 by using sodium hydride instead of sodium ethoxide.</jats:p>