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Titolo:
Medium-sized cyclophanes. Part 53. Synthesis and conformational studies, and photoinduced cyclization of syn-[n.2]metacyclophanenes
Autore:
Yamato, T; Fujita, K; Futatsuki, K; Tsuzuki, H;
Indirizzi:
Saga Univ, Fac Sci & Engn, Dept Appl Chem, Saga 8408502, Japan Saga Univ Saga Japan 8408502 & Engn, Dept Appl Chem, Saga 8408502, Japan Tohwa Univ, Tohwa Inst Sci, Ctr Environm Anal, Minami Ku, Fukuoka 8158510,Japan Tohwa Univ Fukuoka Japan 8158510 Anal, Minami Ku, Fukuoka 8158510,Japan
Titolo Testata:
CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE
fascicolo: 8, volume: 78, anno: 2000,
pagine: 1089 - 1099
SICI:
0008-4042(200008)78:8<1089:MCP5SA>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
LOW-VALENT TITANIUM; CONVENIENT SYNTHESIS; SELECTIVE PREPARATION; COUPLING REACTIONS; CRYSTAL-STRUCTURE; METACYCLOPHANES; 8-METHOXY<2.2>METACYCLOPHANES; STEREOCHEMISTRY; REDUCTION; BENZENE;
Keywords:
cyclophanes; strained molecule; McMurry reaction; C-C coupling; conformation analysis; cyclizations; photolysis; transannular reactions; transition states;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
94
Recensione:
Indirizzi per estratti:
Indirizzo: Yamato, T Saga Univ, Fac Sci & Engn, Dept Appl Chem, Honjo Machi 1, Saga 8408502, Japan Saga Univ Honjo Machi 1 Saga Japan 8408502 Saga 8408502, Japan
Citazione:
T. Yamato et al., "Medium-sized cyclophanes. Part 53. Synthesis and conformational studies, and photoinduced cyclization of syn-[n.2]metacyclophanenes", CAN J CHEM, 78(8), 2000, pp. 1089-1099

Abstract

A series of [n.2]metacyclophanenes (3) and (6) were prepared in good yields by a McMurry cyclization of 1,n-bis(3-acetyl-4-methoxyphenyl)alkanes (2) and 1,3-bis(3-formyl-4-methoxyphenyl)propane (5), respectively. Compounds 3b, 3c exist in the syn-conformation due to the steric repulsion between themethyl groups at the ethano bridge and the methoxy groups at the aromatic rings while compound 6 prefers the anti-conformation typical of [3.2]metacyclo- phanes. The assignment of syn-conformations has been confirmed by H-1 NMR analyses and X-ray diffraction studies. Photoinduced transannular cyclization of [n.2]metacyclophanenes (3) and (6) in the presence of iodine as an oxidant afforded phenanthrene-anellated polycyclic aromatic hydrocarbons. Apparently, the rate of the photocyclization of anti-6 was found to be much faster than that of syn-3b and almost completed within 1 h. Thus, the different reactivities for the irradiation of syn- and anti-conformer were observed. The reason for the present preference for the formation of trans-dihydrophenanthrene rather than cis-dihydrophenanthrene as the intermediate might be attributable to the more stable chair form transition state than boat one and the conformational fixation to the chair form in the ground and transition state is possible in the anti-conformer.

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Documento generato il 06/04/20 alle ore 23:52:34