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Titolo:
1-MAGNESIOTETRAHYDROISOQUINOLYLOXAZOLINES AS CHIRAL NUCLEOPHILES IN STEREOSELECTIVE ADDITIONS TO ALDEHYDES - AUXILIARY OPTIMIZATION, ASYMMETRIC-SYNTHESIS OF (-CORLUMINE, (+)-BICUCULLINE, (+)-EGENINE, AND (+)-CORYTENSINE, AND PRELIMINARY C-13 NMR-STUDIES OF 1-LITHIOTETRAHYDROISOQUINOLYLOXAZOLINES AND 1-MAGNESIOTETRAHYDROISOQUINOLYLOXAZOLINES())
Autore:
GAWLEY RE; ZHANG PS;
Indirizzi:
UNIV MIAMI,DEPT CHEM CORAL GABLES FL 33124
Titolo Testata:
Journal of organic chemistry
fascicolo: 23, volume: 61, anno: 1996,
pagine: 8103 - 8112
SICI:
0022-3263(1996)61:23<8103:1ACNIS>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
DIPOLE-STABILIZED ANIONS; ORGANO-LITHIUM COMPOUNDS; ENANTIOSELECTIVE SYNTHESIS; CARBONYL ADDITION; SPECTROSCOPY; STEREOCHEMISTRY; DEPROTONATIONS; BUTYLLITHIUM; ALKYLATION; EXCHANGE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
60
Recensione:
Indirizzi per estratti:
Citazione:
R.E. Gawley e P.S. Zhang, "1-MAGNESIOTETRAHYDROISOQUINOLYLOXAZOLINES AS CHIRAL NUCLEOPHILES IN STEREOSELECTIVE ADDITIONS TO ALDEHYDES - AUXILIARY OPTIMIZATION, ASYMMETRIC-SYNTHESIS OF (-CORLUMINE, (+)-BICUCULLINE, (+)-EGENINE, AND (+)-CORYTENSINE, AND PRELIMINARY C-13 NMR-STUDIES OF 1-LITHIOTETRAHYDROISOQUINOLYLOXAZOLINES AND 1-MAGNESIOTETRAHYDROISOQUINOLYLOXAZOLINES())", Journal of organic chemistry, 61(23), 1996, pp. 8103-8112

Abstract

Transmetalation of 1-lithiotetrahydroisoquinolyloxazolines with magnesium halides affords Grignard reagents that add to aldehydes with up to 80% selectivity for one of the four possible diastereomeric products. An oxazoline chiral auxiliary derived from camphor provides an optimal blend of diastereoselectivity and isomer separability. Synthetic applications of the optimal auxiliary, patterned after a literature approach in the racemic series, comprise an improved (formal) synthesis ofbicuculline, egenine, and corytensine, as well as an efficient synthesis of corlumine. Preliminary NMR studies show that both 1-lithio- and1-magnesiotetrahydroisoquinolyloxazolines are dynamic mixtures in THFsolution at low temperatures. The barrier to pyramidal inversion of the secondary Grignard reagent is in the 9.8-10.1 kcal/mol range, whilean upper limit of about 8.2 kcal/mol can be assigned to the barrier to the organolithium inversion.

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Documento generato il 29/05/20 alle ore 17:00:22