Abstract
A [4+2]-cycloaddition of quinazoline (2) and the 3H-1, 2, 3-triazolo[4, 5-d]pyrimidine 4 with enamines 1a-e resulted in ring transformation into the quinolines, 3a and 3c, and the 3H-1, 2, 3-triazolo[4, 5-b]pyridines, 5a-e, respectively. Similarly, the ynamine 13a cycloadded to 2 and its 4-cyano derivative 6, giving the quinolines, 14a and 14b, respectively.On the other hand, the 3H-1, 2, 3-triazolo[4, 5-d]pyrimidines 4, 15, 8, 16, 17, 18, and 19 underwent [2+2]-cycloaddition with the ynamine 13a, resulting in ring transformation into the corresponding 3H-1, 2, 3-triazolo[4, 5-d]-[1, 3]diazocines 21a-27. The 7-methoxy derivative 20, the 4-methoxy- and 4-cyano-1H-pyrazolo[3, 4-d]pyrimidines, 30 and 31, and the 6-cyano-9H-purine 36 also underwent [2+2]-cycloaddition with 13a to give the corresponding 3H-1, 2-3-triazolo[4, 5-b][1, 5]diazocine 28, 1H-pyrazolo[3, 4-b][1, 5]diazocines, 32 and 33, and 3H-imidazo[4, 5-b]-[1, 5]diazocine 37, respectively.The structures of the 1, 3- and 1, 5-diazocines, 21a and 28, were determined by X-ray crystallography.
