Demethoxycarbonylation of methyl 2,5-di-tert-butyl-1H-azepine-1-carboxylate using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gave 3H-azepines. Under similar conditions, methyl 3,6-ditert-butyl-1H-azepine-1-carboxylate gave not only the 3H-azepine but also the isomerized 2H- and 4H-azepines. Application of the reaction to dimethyl and diisopropyl substituted 1H-azepines showed that bulky alkyl group substitution stabilizes the seven-membered azatriene system. The thermal behaviour of the di-tert-butyl substituted azepines is discussed.
|Number of pages||5|
|Journal||Journal of the Chemical Society, Perkin Transactions 1|
|Publication status||Published - Dec 1 1994|
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