- Gas-phase cyclisation reactions of 1-(2-arylthiophenyl)alkaniminyl and 2-(aryliminomethyl)thiophenoxyl radicals
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Flash vacuum pyrolysis (FVP) of the oxime ethers 12-14 and of the sulfides 18-20 at 650°C (10-2-10-3 Torr) gave products derived from the corresponding iminyl and thiophenoxyl radicals. In all cases, benz[d]isothiazoles (e.g., 26) are formed as major products via SHi mechanisms though the yields are greatest with the iminyl precursors. Alternative pathways observed from the thiophenoxyls in specific cases include the formation of the anilinobenzothiophene 36 and of dibenzothiophene 23, via an SHi process and a spirodienyl rearrangement, respectively. There is no evidence for signicant interconversion of the iminyl and thiophenoxyl species.
- Creed,Leardini,McNab,Nanni,Nicolson,Reed
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p. 1079 - 1085
(2007/10/03)
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- THERMAL FISSION OF HYDROXYLAMINE DERIVATIVES WITH NEIGHBOURING-GROUP-PARTICIPATION BY THIOETHER FUNCTIONS: PREPARATION OF 1,2-BENZISOTHIAZOLES
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Some of the factors influencing the preparation of 1,2-benzisothiazoles from 2-(alkylthio)phenyl-substituted oximes are discussed.Good yields of 3-aryl-1,2-benzisothiazoles 4 may be obtained from readily available precursors.Reaction takes place under particularly mild conditions when a t-butylthio function is situated anti to the leaving group at oxime-nitrogen and S-N overlap is not restricted by ring-strain in the transition-state.The corresponding N-methyl-hydroxamic acid derivatives 2 give good yields of 2-methyl-1,2-benzisothiazol-3(2H)-one 13 only when a t-butylthio substituent is present, e.g. in 2f.The ethylthio- and i-propylthio-analogues 2d and 2e give the vinylthioethers 12, while the methylthio derivatives 2a-c undergo a novel rearrangement to "Pummerer" esters.The preparation of the polycyclic compounds fluoreno-1,2 thiazole 7 and 2,2'-bi(2H-fluoreno-1,3-thiazine) 8 is described.
- Lawson, Alexander J.
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p. 357 - 368
(2007/10/02)
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