Reduction of nitro- and nitroso-compounds by tervalent phosphorus reagents. Part VII. A new synthesis of phenothiazines involving a new molecular rearrangement
作者:J. I. G. Cadogan、S. Kulik、C. Thomson、M. J. Todd
DOI:10.1039/j39700002437
日期:——
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
Synthesis of Diaryl Ethers, Diaryl Thioethers, and Diarylamines Mediated by Potassium Fluoride−Alumina and 18-Crown-6: Expansion of Scope and Utility<sup>1</sup>
作者:J. Scott Sawyer、Elisabeth A. Schmittling、Jayne A. Palkowitz、William J. Smith
DOI:10.1021/jo980800g
日期:1998.9.1
An efficient alternative to the Ullmann ether synthesis of diaryl ethers, diaryl thioethers, and diarylamines involving the SNAr addition of a phenol, thiophenol, or aniline to an appropriate aryl halide, mediated by potassium-fluoride alumina and 18-crown-6 in acetonitrile or DMSO, is described. Expansion of the reaction conditions to include DMSO as solvent has resulted in a far greater range of substitution patterns permitted on the electrophile. For example, it was found that electronically unfavorable S-chlorobenzonitrile could be condensed with 3-methoxyphenol to form the corresponding diaryl ether in 66% yield, a combination not normally amenable to Ullmann coupling. Electron-withdrawing groups present on the electrophile may be as diverse as nitro, cyano, formyl, acetyl, ester, amide, and even aryl. The method features a simple reaction procedure that provides products in generally good to excellent purified yields.
Cadogan,J.I.G. et al., Journal of the Chemical Society. Perkin transactions I, 1976, p. 1749 - 1757