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Titolo:
STRAIGHTFORWARD SYNTHESES OF BIRADICAL-PRODUCING BICYCLIC DIENEDIYNES- DIENEDIYNE KETONES CYCLOAROMATIZE VIA THE SAITO-MYERS AND NOT VIA THE NEOCARZINOSTATIN PATHWAY
Autore:
FERRI F; BRUCKNER R; HERGES R;
Indirizzi:
UNIV GOTTINGEN,INST ORGAN CHEM,TAMMANNSTR 2 D-37077 GOTTINGEN GERMANY UNIV GOTTINGEN,INST ORGAN CHEM D-37077 GOTTINGEN GERMANY TECH UNIV CAROLO WILHELMINA BRAUNSCHWEIG,INST ORGAN CHEM D-38106 BRAUNSCHWEIG GERMANY
Titolo Testata:
New journal of chemistry
fascicolo: 5, volume: 22, anno: 1998,
pagine: 531 - 545
SICI:
1144-0546(1998)22:5<531:SSOBBD>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
2ND-ORDER PERTURBATION-THEORY; CASCADE RADICAL CYCLIZATIONS; 6-/10-MEMBERED RING ANALOGS; ENEDIYNE MODEL COMPOUNDS; DNA-CLEAVING AGENTS; LOW-VALENT TITANIUM; ENYNE-ALLENES; CHROMOPHORE ANALOG; ESPERAMICIN-CALICHEMICIN; ISOMERIZATION REACTION;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
103
Recensione:
Indirizzi per estratti:
Citazione:
F. Ferri et al., "STRAIGHTFORWARD SYNTHESES OF BIRADICAL-PRODUCING BICYCLIC DIENEDIYNES- DIENEDIYNE KETONES CYCLOAROMATIZE VIA THE SAITO-MYERS AND NOT VIA THE NEOCARZINOSTATIN PATHWAY", New journal of chemistry, 22(5), 1998, pp. 531-545

Abstract

The dienediyne models 23 and 28 of the pharmacophore of the antitumornatural product neocarzinostatin were prepared. Each synthesis requires only six steps from alpha-formylcyclohexanone. Our approach uses two key steps. The first consists of one-pot biscoupling reactions between propargyl alcohol, 2,2-dimethyl-3-butyn-1-ol and the bis(enoltrifluoromethanesulfonate) 17. The second key step corresponds to ring-closing pinacol coupling reactions of the dialdehydes 20 and 25. The dienediyne models 23 and 28 cycloaromatized efficiently when treated with methyl thioglycolate and 1,4-cyclohexadiene at 25 degrees C via a Saito-Myers cyclization(4) (to give the octahydroanthracenones 29, iso-29 and octahydrophenanthrenones 34, 35, respectively); in addition, we isolated compounds tentatively assigned as the octahydrobenzazulenones 30 and iso-30, which would stem from a competing Schmittel cyclization, According to density functional theory (B3LYP/6-31G) and ab initio calculations [CASMP2(2.2)/6-31G//CAS(2.2)/6-31G], the core structures of the octahydroanthracenones and octahydrophenanthrenones obtained here and elsewhere form via the Saito-Myers cyclization of enyneallenyl ketones 53 to toluene-alpha,meta biradicals 55 and not via neocarzinostatin-like cycloaromatizations of the tautomeric enyne[3]cumulenols 54 tostyrene alpha,meta-biradicals 56. This is so because, on the one hand, the two cyclization modes are predicted to have similar activation barriers (Saito-Myers: 16.0 kcal mol(-1); neocarzinostatin type: 18.3 kcal mol(-1)) but, on the other hand, the enyneallenyl ketone 53 is a much more stable (21.1 kcal mol(-1)) cycloaromatization substrate than the enynecumulenol 54. In addition, the Saito-Myers cyclization product 55 is calculated to be considerably more stable (35.3 kcal mol(-1)) than the neocarzinostatin-type cycloaromatization product 56.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/04/20 alle ore 21:40:48