<Regular Article>Reactions of 10-Alkyl- and 10-Aryl-9-phenylthioxanthenium Salts with Various Bases : 1,4-Sigmatropic Rearrangement of 10-Alkyl- and 10-Aryl-9-phenyl-9-thiaanthracenes

A 1,4-sigmatropic rearrangement of 10-alkyl and 10-aryl-9-phenyl-10-thiaanthracenes is described. 10-(4-Methoxyphenyl)-9-phenyl-10-thiaanthracene generated by proton abstraction of 10-(4-methoxyphenyl)-9-phenylthioxanthenium perchlorate (1a) with bases such as sodium dimsylate, sodium methoxide, sodium hydride, and Grignard reagent underwent 1,4-rearrangement to afford 9-(4-methoxyphenyl)-9-phenylthioxanthene (2a) in high yield. The deprotonation of 1a with organolithiums such as phenyllithium or methyllithium afforded 9,9-diphenylthioxanthene ( 3 ) or 9-methyl-9-phenylthioxanthene (2d) via ligand-exchanged thiaanthracene intermediates generated in situ, along with 2a. Other 10-alkyl or 10-aryl-9-phenylthiaanthracenes generated from the corresponding thioxanthenium salts (1b-g) by treatment with base also decomposed thermally to give 1,4-rearranged products 2b-g in good yield. These 1,4-rearrangements were found to be intramolecular 1,4-sigmatropic rearrangements by cross over experiments

<Regular Article>Reactions of 10-Alkyl- and 10-Aryl-9-phenylthioxanthenium Salts with Various Bases : 1,4-Sigmatropic Rearrangement of 10-Alkyl- and 10-Aryl-9-phenyl-9-thiaanthracenes

A 1,4-sigmatropic rearrangement of 10-alkyl and 10-aryl-9-phenyl-10-thiaanthracenes is described. 10-(4-Methoxyphenyl)-9-phenyl-10-thiaanthracene generated by proton abstraction of 10-(4-methoxyphenyl)-9-phenylthioxanthenium perchlorate (1a) with bases such as sodium dimsylate, sodium methoxide, sodium hydride, and Grignard reagent underwent 1,4-rearrangement to afford 9-(4-methoxyphenyl)-9-phenylthioxanthene (2a) in high yield. The deprotonation of 1a with organolithiums such as phenyllithium or methyllithium afforded 9,9-diphenylthioxanthene ( 3 ) or 9-methyl-9-phenylthioxanthene (2d) via ligand-exchanged thiaanthracene intermediates generated in situ, along with 2a. Other 10-alkyl or 10-aryl-9-phenylthiaanthracenes generated from the corresponding thioxanthenium salts (1b-g) by treatment with base also decomposed thermally to give 1,4-rearranged products 2b-g in good yield. These 1,4-rearrangements were found to be intramolecular 1,4-sigmatropic rearrangements by cross over experiments