1, 5, 6, 7-Tetrahydro-2H-[1,4]diazepin-5,7-dione aus Malonimiden und 3-Dimethylamino-2,2-dimethyl-2H-azirin

1, 5, 6, 7-Tetrahydro-2H-[1, 4]diazepin-5, 7-diones from Malonimides and 3-Dimethylamino-2, 2-dimethyl-2H-azirine Reaction of the aminoazirine 1 with malonimides of type 7 in 2-propanol at room temperature leads to the 1,4-diazepine derivatives of type 9 (Scheme 3). The structure of 6, 6-diethyl-3-dimethylamino-2,2-dimethyl-1,5,6, 7-tetrahydro-2H- [1,4] diazepin-5, 7-dione ( 9a ) has been proved by single crystal X-ray analysis (Chapter 4). Reduction of the 7-membered heterocycle 9a with sodium borohydride yields the perhydro-[1,4]diazepin-5, 7-dione 10 , while 9a in ethanol at 60° undergoes a ring contraction to the 4 H-imidazole derivative 11a (Scheme 4): Mechanisms of these two reactions are discussed in comparison with previously reported reactions (Chapter 5).