Seven-membered Rings containing Three or More Heteroatoms

5 Seven-membered Rings containing Three or More Heteroatoms 

Diphenyl sulphur di-imide (338) and diphenylketen react to give a 1 2 adduct at 6-8 viz, the thiadiazepine (339), W the compound is unstable and decomposes on warming to form the 1 1 adduct (340) plus diphenyl-keten. In an interesting one-pot reaction, cyclic iViV -disubstituted 

Reaction of hydrazoic acid with the monoaryl sulphoxides (345) affords benzothiazine oxides (346) and benzothiadiazepine oxides (347), and the same reagent converts the diaryl sulphoxides (348) into the benzothiadiazine oxides (349), which undergo a base-catalysed rearrangement to (350), cf. (228) - (229a). JV-5-Alkylation of the latter occurs on treatment with sodamide and alkyl halides, and reduction of the lactam moiety is brought about by LiAlH4.  

Benzothiadiazepine dioxides (351) have been obtained by reaction of o-bromomethyl-iV-(n-hexyl)benzenesulphonamide with alkyl nitriles in the 

Reaction of iViV -disubstituted hydrazines with /SjS -dichlorodiethylether in base at 145 C gives the oxadiazepines (356), and treatment of (357), 

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