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Titolo:
REARRANGEMENT OF A BICYCLO[3.2.0]HEPT-2-ENE TO A BICYCLO[4.1.0]HEPT-4-ENE
Autore:
BEHRENDT U; GABOR B; MYNOTT R; BUTENSCHON H;
Indirizzi:
UNIV HANNOVER,INST ORGAN CHEM,SCHNEIDERBERG 1B D-30167 HANNOVER GERMANY MAX PLANCK INST KOHLENFORSCH D-45470 MULHEIM GERMANY
Titolo Testata:
Liebigs Annalen
fascicolo: 7, , anno: 1996,
pagine: 1167 - 1173
SICI:
0947-3440(1996):7<1167:ROABTA>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
DERIVATIVES; CYCLOADDITION;
Keywords:
REARRANGEMENTS; BICYCLO[3.2.0]HEPT-2-EN-ONE; BICYCLO[4.1.0]HEPT-4-EN-1-OL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
15
Recensione:
Indirizzi per estratti:
Citazione:
U. Behrendt et al., "REARRANGEMENT OF A BICYCLO[3.2.0]HEPT-2-ENE TO A BICYCLO[4.1.0]HEPT-4-ENE", Liebigs Annalen, (7), 1996, pp. 1167-1173

Abstract

The chemistry of the highly substituted cyclobutanone derivative 2, which is easily accessible from 1, is dominated by the steric hindrancecaused by the substituents: Reduction with hydride reagents and nucleophilic additions with methyllithium are less stereoselective than corresponding reactions with less substituted bicyclo[3.2.0]hept-2-en-6-one derivatives, but under certain conditions, the exo product predominates. With methyl-, benzyl-, ethenyl-, and ethynylmagnesium halides nonucleophilic addition at the carbonyl group is observed, presumably as a result of the steric hindrance. Instead, an unexpected rearrangement to the bicyclo[4.1.0]heptane carbon skeleton occurs with complete diastereoselectivity and high yields. The rearrangement is rationalizedby an increase of the carbocationic character of the carbonyl carbon atom as a result of a coordination of the carbonyl oxygen atom at the Lewis acidic magnesium. This facilitates rearrangement of a cyclobutylcarbenium ion to a cyclopropylmethyl carbenium ion, the latter being stabilized by the amino group. Remarkably, with Grignard reagents derived from propargyl or allyl halides, no rearrangement is observed. Theconstitutions and configurations of the products were determined by H-1- and C-13-NMR spectroscopy using techniques including NOESY and 2D-INADEQUATE.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 18:59:02