Abstract
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 4H-imidazole derivative 11a (Scheme 4): Mechanisms of these two reactions are discussed in comparison with previously reported reactions (Chapter 5).
Scholl, Bernhard