1,2-Sulphur shift in the acid-catalysed cyclisation of o-arylthiophenyl-substituted carbinols to thioxanthen derivatives
- 1 January 1973
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- p. 2250-2253
- https://doi.org/10.1039/p19730002250
Abstract
During the acid-catalysed cyclisation of some o-arylthiophenyl-substituted carbinols to thioxanthen derivatives, arearrangement was observed with carbinols having a para-methyl substituentin thearylthio-group. Thus, 1-[o-(p-tolylthio)phenyl]ethanol gave 3,9-dimethylthioxanthen, while α-[o-(p-tolylthio)phenyl]benzyl alcohol gave a mixture of 3-methyl- and 2-methyl-9-phenylthioxanthen. The mechanism of the cyclisation is discussed in terms of a competition between ring-closure at the position ortho to the sulphur (ortho-substitution) and ring-closure at the position bearing the sulphur followed by a 1,2-sulphur shift (ipso-substitution).Keywords
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