80404-82-6Relevant articles and documents
A general and efficient method for the synthesis of 9-trifluoromethylated [1,2,4]triazolo[1,5-a]azepine derivatives
Ding, Zongbiao,Xia, Shijing,Ji, Xiaojun,Yang, Haiyan,Tao, Fenggang,Wang, Quanrui
, p. 349 - 354 (2007/10/03)
(1-Chloro-2-trifluoromethylcyclohexyl)azo compounds 3a - d, prepared by oxidation of the hydrazones 2a - d of 2-trifluoromethylcyclohexanone (1) with a slightly excess amount of tert-butyl hypochlorite, react with antimony pentachloride and a nitrile to afford the respective 2,3-disubstituted-9-trifluoromethyl-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo [1,5-a]azepinium hexachloroantimonates 6a - j. The reaction mechanism comprises of the initial cycloaddition of the in situ generated 1-aza-2-azoniaallene salts 4 to the triple bond of nitrile, giving the spiro-substituted 5a - j, followed by rearrangement and concomitant ring enlargement. From 3a - c where R1 = aryl, the salts 6a - h are isolated in high yields. However, if ethyl (1-chloro-2-trifluoromethyl)azocarboxylate (3d) is employed, the neutral N(3)-unsubstituted analogues 7a and 7b are obtained and after usual basic work-up, are converted to picrates 8a and 8b respectively. For one compound 6f, the X-ray diffraction analysis has been carried out in order to confirm the structural assignment. A practical modified procedure for preparation of the crucial starting ketone 1 is also described.
