Versuche zur Oxidation von 1.5-Benzothiazepin — bzw. 1.5-Benzoxazepin- 2.4-3H.5H-dionen / Investigations Concerning Oxidation Reactions of 1,5-Benzthiazepin — and 1,5-Benzoxazepin- 2,4-3H,5H -diones

Attempts to oxidize the 1,5-benzothiazepin-2,4-3H,5H-dione (1) using NaNO2/Acetic acid lead to isolation of two ring contracted products, namely the 1,4-benzthiazin-derivatives 4 and 5. A reasonable reaction pathway concerning the formation of these compounds is discussed. A simple synthesis of 6-methyI-1,5-benzoxazepin-2,4-3H,5H-dione (13) is described, the transformation of which into the corresponding vic. trione fails, even using a great number of oxidizing procedures. In some cases so far unknown malonic acid derivatives 14, 15 and 16 can be obtained.