Base-induced dehalogenation of aryl halides in tert-butyl alcohol-dimethyl sulfoxide and similar solvent mixtures

Abstract

Sir :Moyer discovered that lY2,4-tribromobenzene, on exposure to excess potassium t-butoxide (t-BuO-K+) in 50 % t-butyl alcohol-50 % dimethyl sulfoxide (DMSO) at 53", suffered reductive loss of the 2-bromine. p-Dibromobenzene was formed in 70%.yield, and the bromine removed appeared as bromide ion. We have studied this unusual reaction and obtained evidence indicating its mechanism. h r Br 70 % A number of chloro, bromo, and/or iodo derivatives of benzene are partially and selectively dehalogenated by this reagent. In general, protodehalogenation occurs only at sites ortho to other halogen atoms and is most facile for halogens flanked on both sides by ortho halogens. Other things being equal, deiodination occurs more readily than debromination, while dechlorination has not been observed. Electron-attracting substituents facilitate the reaction. Representative yields are 99 % m-dibromobenzene from 1,2,3-tribromo-(1) C. E. Moyer, Jr., Dissertation, Brown University, 1964; Dissertotion Abstr., 25, 4412 (1965).

Superbase‐Mediated Indirect Friedländer Reaction: A Transition Metal‐Free Oxidative Annulation toward Functionalized Quinolines

“…Contrary to our expectation of 2‐(4‐chlorophenyl)quinoline 3k , we obtained a dehalogenated quinoline derivative. The dehalogenation of aromatic compounds with a DMSO‐base combination was reported earlier which might be the reason for the present observation . The oxidative annulation also worked with acetylferrocene affording 2‐ferrocenylquinoline 3l in 45 % yield.…”

Reações de ortometalacão em piridinas

“…Os mecanismos destas transferências ("dança dos halogênios") [25][26][27] , responsáveis pela isomerização, são suficientemente rápidos e reversíveis para que as espécies litiadas do tipo I e II estejam praticamente em equilíbrio (Esquema 10). Os parâmetros deste equilíbrio (efeito indutivo destes halogênios, estabilização das espécies litiadas segundo a posição e estabilidade das ligações C-X), foram objetos de estudos teóricos detalhados 18,[23][24][25]28,29 .…”

“…Os parâmetros deste equilíbrio (efeito indutivo destes halogênios, estabilização das espécies litiadas segundo a posição e estabilidade das ligações C-X), foram objetos de estudos teóricos detalhados 18,[23][24][25]28,29 .…”

Terminal versus Internal Diiodobenzyl Alcohol Derivatives via Regioselective Metal–Iodine Exchange of 1,2,3‐Triiodoarenes: Synthesis and Antibacterial Activity

“…The regioselective metal-halogen exchange reaction of dibromo-and tribromoarene derivatives is well documented. [21][22][23][24]27,[35][36][37][38] Interestingly, there are only a few examples of the metal-halogen exchange reaction on diiodoarenes and triiodoarenes. 8,20,39,40 This lack of investigations could be attributed to the accessibility and availability of diiodo-and triiodoarenes.…”