REACTIVITY OF REDUCED AZEPINE SYSTEMS

The regiochemistry of the cycloaddition step has been elucidated with deuterated 1-methyl-1//-azepin-3(27/)-one. 

Photolysis of 1-phenyl-l -azepin-3(2//)-one yields the bicyclic compound (53) upon irradiation 90JCS(P1)3169 , whereas lH-azepine-2,7-dione gives a dimer, to which the structure (54) has been attributed 94JHC215 . 

Photolysis of 10.tf-azepino[l,2-a]indole (64) in methanol or ethanol 82JCS(P1)1871 gives respec- 

1-Methyl-l/f-azepin-3(2//)-one gives the O-ethyl derivative (69) on treatment with tri-ethyloxonium tetrafluoroborate 90JCS(P1)3163 . Observation of the rates of deuterium incorporation in pHJtrifluoroacetic acid solution showed sequential deuterium exchange at the 4-, 6-, and 2-positions. Since (69) is unaffected under these conditions over a period of several weeks, it must be assumed that the exchange takes place via the free base. Chlorination of 1-methyl-l//-azepin-3(270-one with one or two equivalents of NCS affords respectively 4-chloro-l-methyl-17/-azepin-3(27 one and 4,6-dichloro-l-methyl-l//-azepin-3(27f)-one. 

A number of interesting reactions have been carried out on ring systems of which the azepine ring is just one example of a number of cyclic amines. For example, treatment of (70) with potassium hexamethyldisilazide in THF at —78°C followed by trisyl azide gives a 65% yield of the /ru/ii-azide (71) 92TL6859 . A phenylseleno derivative is formed in 78% yield when trisyl azide is replaced by phenylselenylchloride. 

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