Polarized ketene dithioacetals. Part 41. Studies on base-catalysed rearrangements of 1,l-bis(alkylthio)-2-aroylpenta-1,4-dienes to novel 1,5-bis(alkylthio)-2-aroylpenta-1,3-dienes via a 1,5-alkylthio shift
- 1 January 1985
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- p. 641-645
- https://doi.org/10.1039/p19850000641
Abstract
1,1-Bis(alkylthio)-2-aroylpenta-1,4-dienes (7a–f) undergo a facile rearrangement in the presence of sodium hydride and dimethylformamide–benzene to give novel (1Z,3E)-1,5-bis(alkylthio)-2-aroylpenta-1,3-dienes (9a–f), respectively. A probable mechanism involving the mobile oxopentadienyl intermediate (12), which on subsequent 1,5-alkylthio shift affords the dienes (9), has been suggested for this highly stereoselective rearrangement. Mechanistic studies have shown that the 1,5-alkylthio shift in this transformation is an intermolecular rather than a concerted process and involves the solvent-equilibriated enolate anion (17) formed by Michael addition of thiolate anion to (12). The synthesis of the α-allyloxoketene dithioacetals (7a–f) is also describedKeywords
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