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Titolo:
CHALCOGEN(IV)-CHALCOGEN(II) REDOX CYCLES .1. HALOGENATION OF ORGANIC SUBSTRATES WITH DIHALOSELENIUM(IV) AND DIHALOTELLURIUM(IV) DERIVATIVES- DEHALOGENATION OF VICINAL DIBROMIDES WITH DIARYL TELLURIDES
Autore:
LEONARD KA; ZHOU F; DETTY MR;
Indirizzi:
SUNY BUFFALO,SCH PHARM,DEPT MED CHEM AMHERST NY 14260 SUNY BUFFALO,SCH PHARM,DEPT MED CHEM AMHERST NY 14260 SUNY BUFFALO,DEPT CHEM AMHERST NY 14260
Titolo Testata:
Organometallics
fascicolo: 20, volume: 15, anno: 1996,
pagine: 4285 - 4292
SICI:
0276-7333(1996)15:20<4285:CRC.HO>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
ORGANOTELLURIUM(II) COMPOUNDS; STEPWISE MECHANISM; OXIDATIVE ADDITION; DEBROMINATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
K.A. Leonard et al., "CHALCOGEN(IV)-CHALCOGEN(II) REDOX CYCLES .1. HALOGENATION OF ORGANIC SUBSTRATES WITH DIHALOSELENIUM(IV) AND DIHALOTELLURIUM(IV) DERIVATIVES- DEHALOGENATION OF VICINAL DIBROMIDES WITH DIARYL TELLURIDES", Organometallics, 15(20), 1996, pp. 4285-4292

Abstract

Dibromodiarylselenium(IV) species were efficient sources of positive bromine for bromolactonization of 4-pentenoic acid, bromocyclization of 4-penten-1-ol and 2-buten-1-ol, bromination of 1,3,5-trimethoxybenzene, and bromination of trans-stilbene and cyclohexene. These reactionswere much slower than brominations with elemental bromine, and product distributions were brominating-agent dependent. Comparable reactionswith the diphenylselenide-iodine complex were kinetically indistinguishable from reactions with elemental iodine. Diiododiaryltellurium(IV)species were efficient sources of positive iodine for iodolactonization of 4-pentenoic acid and for the iodocyclization of 4-penten-1-ol. The rates of iodolactonization decreased with increasing electron donation from substituents on the aryl groups. Dibromodiaryltellurium(IV) derivatives gave trace quantities of bromination products in reactions with olefinic substrates. However, diaryl tellurides gave debromination of erythro-1,2-dibromo-1,2-diphenylethane to give trans-stilbene andthe corresponding dibromodiaryltellurium(IV) derivatives. Electron-donating substituents accelerated the rate of debromination. At identical concentrations, debromination of erythro-1,2-dibromo-1,2-diphenylethane with diaryl telluride and bromination of trans-stilbene with dibromodiaryltellurium(IV) gave identical product mixtures, which is indicative of the equilibrium associated with such halogenation-dehalogenation reactions.

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Documento generato il 03/12/20 alle ore 12:36:33