Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
The steric course of S(E)2 reactions of unstabilized alpha-aminoorganolithiums: Distinguishing between SET and polar mechanisms
Autore:
Gawley, RE; Low, E; Zhang, QH; Harris, R;
Indirizzi:
Univ Miami, Dept Chem, Coral Gables, FL 33124 USA Univ Miami Coral GablesFL USA 33124 ept Chem, Coral Gables, FL 33124 USA
Titolo Testata:
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
fascicolo: 14, volume: 122, anno: 2000,
pagine: 3344 - 3350
SICI:
0002-7863(20000412)122:14<3344:TSCOSR>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
SINGLE-ELECTRON-TRANSFER; SUBSTITUTION-REACTIONS; GRIGNARD-REAGENTS; DEPROTONATION; CARBANIONS; TERTIARY; LITHIUM; AMINES; ANIONS; LITHIOPINACOLONATE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Gawley, RE Univ Miami, Dept Chem, Coral Gables, FL 33124 USA Univ Miami Coral Gables FL USA 33124 oral Gables, FL 33124 USA
Citazione:
R.E. Gawley et al., "The steric course of S(E)2 reactions of unstabilized alpha-aminoorganolithiums: Distinguishing between SET and polar mechanisms", J AM CHEM S, 122(14), 2000, pp. 3344-3350

Abstract

The competing mechanisms that determine the steric course of electrophilicaliphalic substitution reactions (S(E)2) of configurationally stable, unstabilized alpha-aminoorganolithiums are compared. The steric course of the reaction of lithiated pyrrolidines and piperidines with electrophiles is variable, such as when comparisons are made between two electrophiles and a single organolithium, or between two organolithiums and a single electrophile. The possible pathways considered are single electron transfer (SET) and competing polar substitutions (S(E)2ret vs S(E)2inv). Catalysis of organolithium racemization by the electrophile was eliminated as a possible source of racemic products. When the products are completely racemic, our evidence suggests that SET is the most likely mechanism; when polar pathways are operative, stereoselectivities vary from 75 to 100%, and may be invertive or retentive at the carbanionic carbon, depending on the electrophile.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/03/20 alle ore 13:34:19