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You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content. Method 3: Of 1,3,4-Benzotriazepines

DOI: 10.1055/sos-SD-016-00745

Kikelj, D.Science of Synthesis, (200416668.

2-Aryl-3,4-dihydro-5H-1,3,4-benzotriazepin-5-ones undergo oxidative ring contraction with potassium permanganate in anhydrous acetone to give 2-arylquinazolin-4(3H)-ones in good yields (Scheme 143).[‌648‌] Since such ring contraction does not take place in the presence of manganese dioxide, this suggests that the reaction is aided by permanganate anion and proceeds via an intermediate 3-amino-2-arylquinazolin-4(3H)-one. 7-Chloro-5-phenyl-1,3,4-benzotriazepin-2-amines 215 undergo, on reflux in 5M hydrochloric acid or 0.5M ethanolic potassium hydroxide, a ring openingring closure reaction, resulting in overall ring contraction to 6-chloro-2-hydrazino-4-phenylquinazolines 216, which, on further heating, afford 6-chloro-4-phenylquinazolin-2(1H)-one (217) (Scheme 144).[‌649‌]

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