Lithium/ ammonia reductions of 2-thiophenecarboxylic acids (1) in the absence of a proton source afforded mixtures of products. In the presence of methanol acyclic mercapto carboxylic acids (4) were the major products. Ring closure of 4 to the corresponding thiolactones (12) showed the double bonds in 4 to be of cis geometry. Attempts were made to prepare Z olefinic compounds derived from these mercapto carboxylic acids. Lithium 2thiophenecarboxylate salts (2) afforded good yields of the corresponding 2,5-dihydro-2-thiophenecarboxylic acids (3). The presence of substituents on the ring and the ratio of metal to acid were significant factors in determining the nature of the products. A mechanism is proposed to explain the products observed.
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