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Intramolekulare Cycloaddition von Nitronen
Author(s) -
Aurich Hans Günter,
Boutahar Mostafa,
Köster Heiner,
Möbus KlausDieter,
Ruiz Luis
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901231011
Subject(s) - cycloaddition , bicyclic molecule , chemistry , nitrone , intramolecular force , toluene , medicinal chemistry , yield (engineering) , stereochemistry , organic chemistry , catalysis , metallurgy , materials science
Intramolecular Cycloaddition of Nitrones Nitrones 9 and 10 , formed by treatment of the corresponding aldehydes with N ‐substituted hydroxylamines, are converted into the cis fused bicyclic compounds 11 and 12 , respectively. While this intramolecular cycloaddition as a rule occurs at room temperature, the formation of compounds 17/18 and/or 20/21 from the corresponding nitrones needs refluxing in toluene with exception of 17Ca . The N ‐aryl‐substituted nitrones 14C/15C form dimers 22C/23C spontanously at room temperature. However, dimerization is reversible; thus 22/23C afford the bicyclic compounds 17/18 and/or 20/21 on heating in toluene via the corresponding nitrone intermediates. — Hydrogenation cleaves isoxazolidine ring of the bicyclic compounds. Thus, 17Ca and 18Ca yield the hexahydrothiepine 27C and oxepane derivatives 28C , respectively, 21Ca gives the tetrahydropyran 30C . Diastereomerically pure 29C arises by prolonged hydrogenation of 17Ca under reinforced conditions via 27C .