Reduction of nitro- and nitroso-compounds by tervalent phosphorus reagents. Part VII. A new synthesis of phenothiazines involving a new molecular rearrangement
- 1 January 1970
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society C: Organic
- No. 18,p. 2437-2441
- https://doi.org/10.1039/j39700002437
Abstract
Reductive cyclisation of aryl 2-nitroaryl sulphides by triethyl phosphite provides a new synthesis of phenothiazines (yields ca. 50–85%) which is superior to that involving the thermal decomposition of aryl 2-azidoaryl sulphides (yields ca. 30%). Both reactions proceed via a novel molecular rearrangement whereby, for example, 4-chlorophenyl 2-nitrophenyl sulphide gives 3-chlorophenothiazine, whereas 4-chloro-2-nitrophenyl phenyl sulphide gives 2-chlorophenothiazine. [4-2H]phenyl 2-nitrophenyl sulphide similarly gives [3-2H]phenothiazine, as shown by comparison of the e.s.r. spectrum of its cation-radical with those computer-simulated for [2-2H]- and [3-2H]-phenothiazine. A convenient N-ethylation of phenothiazines by triethyl phosphate is also reported.Keywords
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