Reactivity of diazoazoles with electron-rich double bonds

Synthesis of a New Series of Biphenyl-substituted, Fused 1,2,4-triazoles by Oxidative Cyclisation and Dimroth Rearrangement

“…In addition, they exhibited multiplets in the 6.61-8.61 ppm region due to the aromatic protons as well as singlets at 8.36-8.67 ppm due to the hydrazone azomethine protons (-CH=N-). [20][21][22][23][24][25] To provide decisive evidence for this rearrangement, one of the products namely 9a, was compared with an authentic sample prepared by alternate synthesis. in ethanol at 45 °C provided the desired 3-substituted-9-(1,1-biphenyl-4-yl)-7-phenyl-7H-pyrazolo[4,3-e] [1,2,4]triazolo [4,3-c]pyrimidines 8a-f in 40-75% yields.…”

“…This feature is consistent with literature reports which indicate that the pyrimidine ring proton (H-5) in thieno [3,2- 20 The conversion of 8a-f into 9a-f is analogous to the rearrangement of 1,2,4-triazolo [4,3-a] pyrimidines in alkali to the isomeric 1,2,4-triazolo [1,5-a]pyrimidines. [20][21][22][23][24][25] To provide decisive evidence for this rearrangement, one of the products namely 9a, was compared with an authentic sample prepared by alternate synthesis. 26 Thus, treatment of 5 with an equivalent quantity of benzoyl chloride in pyridine gave a single product which proved to be identical in all respects (m.p., mixed m.p., IR and 1 H NMR spectra) with that obtained above from the base-catalysed rearrangement of 8a (Scheme 2).…”

A Semiempirical PM3 Treatment of Benzotetrazepinone Decomposition in Acid Media

“…The PM3 method was used exclusively in this study because semiempirical methods, − and the PM3 method in particular, − have proven accurate for predicting numerous other nitrogen heterocyclic properties. Previous theoretical work has shown PM3 to be the best semiempirical method for reproducing benzotetrazepinone X-ray geometries …”

“…Specifically, this work investigates (a) the possible mechanisms of acid-induced BTZ ring opening, (b) the effect of aryl ring substituents on the acid-induced BTZ ring opening to DPMU, (c) the effect of aryl ring substituents on the formation of BTZs from DPMU, (d) the effect of aryl ring substituents on BTZ synthetic yields, and (e) the formation of NCBT instead of BTZ from DPMU with R ) H as the N5 substituent. The PM3 5 method was used exclusively in this study because semiempirical methods, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and the PM3 method in particular, [24][25][26][27][28][29][30][31][32] have proven accurate for predicting numerous other nitrogen heterocyclic properties. Previous theoretical work has shown PM3 to be the best semiempirical method for reproducing benzotetrazepinone X-ray geometries.…”