The reaction of 5-tert-butyl-2-methoxy-3H-azepine (2a) with sodium alkoxides gave 2-alkoxy-3H-azepine derivatives 3–6 by nucleophilic transetherification. The treatment of 2a with tert-butyllithium also yielded 2,5-di-tert-butyl-3H-azepine (7); however, the reaction of 2a and methyllithium gave the expected 5-tert-butyl-2-methyl-3H-azepine (8) along with unexpected 5-tert-butyl-2,2-dimethyl-2,3-dihydro-1H-azepine
A new ringcontraction reaction giving pyridine derivatives from 3,6- and 2,5-di-tert-butyl-3H-azepines was observed by a successive treatment with bromine and aqueous K2CO3. A plausible mechanism via azatropilium cation for the rearrangement was discussed based on the product’s distribution from respective 3H-azepines.
Demethoxycarbonylation of methyl 2,5,-di-tert-butyl-1H-azepine-1-carboxylate using 1,8-diazabicyclo[5.4.0]undec-7-ene gives exclusively two isomers of 3H-azepinederivatives, while methyl 3,6-di-tert-butyl-1H-azepine-1-carboxylate gives a mixture of 2H-, 3H- and 4H-azepine derivatives under the same conditions because of a 1,5-hydrogen shift in the resulting triene system.
Di-t-butyl derivatives of 3a,5a-dihydro-3H-cyclobuta[b]pyrroles, synthesized from photoisomers of 1H-azepine derivatives (Dewar azepines), isomerizedthermally to 3H-azepines.
由1 H-氮杂环庚烷衍生物(杜瓦·阿塞拜疆)的光异构体合成的3a,5a-二氢-3 H-环丁[ b ]吡咯的二叔丁基衍生物热异构化为3 H-氮杂。
Photochemical behavior of 2,5-di-tert-butyl-3H-azepine: unexpected formation of a dicyclopenta[b,e]pyridine derivative and a cis,cis-cyclodeca-1,6-diene derivative
Hitherto unknown photochemical behavior of 3H-azepine giving cyclopent[c]azete and a (4π + 4π) photodimer is reported on the basis of an unexpected formation of a tricyclic dicyclopenta[b,e]pyridine derivative and a ten-membered-ring dicarbaldehyde by irradiation of 2,5-di-tert-butyl-3H-azepine in hexane.