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Titolo:
Toward novel antioxidants: Preparation of dihydrotellurophenes and selenophenes by alkyltelluride-mediated tandem S(RN)1/S(H)i reactions
Autore:
Engman, L; Laws, MJ; Malmstrom, J; Schiesser, CH; Zugaro, LM;
Indirizzi:
Univ Uppsala, Inst Chem, Dept Organ Chem, S-75121 Uppsala, Sweden Univ Uppsala Uppsala Sweden S-75121 Organ Chem, S-75121 Uppsala, Sweden Univ Melbourne, Sch Chem, Parkville, Vic 3052, Australia Univ Melbourne Parkville Vic Australia 3052 arkville, Vic 3052, Australia
Titolo Testata:
JOURNAL OF ORGANIC CHEMISTRY
fascicolo: 18, volume: 64, anno: 1999,
pagine: 6764 - 6770
SICI:
0022-3263(19990903)64:18<6764:TNAPOD>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
RADICAL HOMOLYTIC SUBSTITUTION; SELENIUM-CONTAINING HETEROCYCLES; THIOL PEROXIDASE-ACTIVITY; PRIMARY ALKYL RADICALS; RATE CONSTANTS; ORGANOTELLURIUM COMPOUNDS; DIARYL DITELLURIDES; LIPID-PEROXIDATION; ELECTRON-TRANSFER; AB-INITIO;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Engman, L Univ Uppsala, Inst Chem, Dept Organ Chem, Box 531, S-75121 Uppsala, Sweden Univ Uppsala Box 531 Uppsala Sweden S-75121 121 Uppsala, Sweden
Citazione:
L. Engman et al., "Toward novel antioxidants: Preparation of dihydrotellurophenes and selenophenes by alkyltelluride-mediated tandem S(RN)1/S(H)i reactions", J ORG CHEM, 64(18), 1999, pp. 6764-6770

Abstract

Reaction of 1-(2-iodophenyl)-1-methyloxirane (12) with 2 equiv of sodium n-butyltellurolate (n-BuTeNa), generated by the sodium borohydride reductionof di-n-butyl ditelluride, in TNF, affords 2,2,3-dihydro-3-hydroxy-3-methylbenzo[b]tellurophene (13) in 62% yield, together with a small quantity of 1-(n-butyltelluro)-2-phenyl-2-propanol (27). This transformation presumablyinvolves a tandem S(RN)1/S(H)i sequence. Similar reactions of 1-(benzylseleno)-2-phenyl-2-propanol (5a, R = Me) and 1-allyloxy-2-iodobenzene (15) afforded 2,3-dihydro-3-hydroxy-3-methylbenzo[b]selenophene (17, 74%), and 3-(n-butyltelluro)methyl-2,3-dihydrobenzo[b]furan (18, 50%), respectively. Lithium alkyltellurolates, generated by direct tellurium insertion into the required alkyllithium, or sec-butyl or tert-butyl substitution on tellurium provide produce distributions similar to those observed for reactions involving n-BuTeNa. Lithium or sodium phenyltellurolate returned only starting materials from these reaction mixtures. The 2-[2-(n-butyltelluro)-1-hydroxy-1-methyl]ethylphenyl radical (14) is estimated to cyclize with k(c) = 5 x 10(8) s(-1) at 25 degrees C. The tandem S(RN)1/S(H)i sequence has been appliedto the preparation of the antioxidant analogues, 5-hydroxy-2,3-dihydrobenzo[b]telluraphene and selenophene (31, 32).

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Documento generato il 03/12/20 alle ore 06:11:09