A novel s-tetrazine assembly

The ‘inverse electron-demand' Diels–Alder reaction in polymer synthesis. Part 4.1 The preparation and crystal structures of some bis(1,2,4,5-tetrazines)

“…3,6-Bis(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine 4, which is simply prepared from triaminoguanidine and acetylacetone with subsequent oxidation of the resulting dihydrotetrazine intermediate, 11 was the starting compound for these studies. The observation 11 that 3-amino-6-(dimethylpyrazol-1-yl)tetrazine 5 is obtained exclusively and in excellent yield when † An earlier report, 7 claiming the synthesis of this compound via the thermolysis of the azo(phenyltetrazine) 3, is open to question. The product is clearly different from 2, both in physical characteristics and chemical reactivity, and no evidence is presented in the paper even to support the structure 3 for the precursor.…”

“…C 12 H 17 N 7 requires C, 55.6; H, 6.6; N, 37.8%). δ H 1.62-1.80 (6H, m, 2 × βand γ-CH 2 of piperidine), 2.33 and 2.52 (each 3H, s, 2 × Me), 3.94-4.02 (4H, m, 2 × α-CH 2 of piperidine), 6.09 (1H, s, 4Ј-H); δ C 13.8 and 14.2 (2 × Me), 24.9 (2 × γ-CH 2 ), 25.9 (2 × β-CH 2 ), 45.2 (2 × α-CH 2 ), 109.8 (C-4Ј), 142.2 (C-5Ј), 152.3 (C-3Ј), 158.0 (C-3), 161.6 (C-6); m/z 259 (M ϩؒ , 22%), 244 (3), 121 (7), 110 (43), 96 (100), 95 (87) and 84 (24).…”

1,3- and 1,4-Substituted tetrazolium salts

“…29 1,4,5-Trisubstituted tetrazolium salts 93a,b undergo N-dealkylation 98 or fragmentation in the presence of bases, 25,101 and ring-opening products always contain alkyl or aryl azide. 1,4,5-Trialkyltetrazolium salts 94 undergo deprotonation under the action of sodium hydride in tetrahydrofuran.…”

“…3,5-Diaryl-1-methyltetrazolium salts 92 are resistant to the action of Et 3 N in toluene at 20 8C, but react vigorously with sodium ethoxide in benzene or toluene to yield a complex mixture of reaction products among which biaryls are predominant. 29 1,4,5-Trisubstituted tetrazolium salts 93a,b undergo N-dealkylation 98 or fragmentation in the presence of bases, 25,101 and ring-opening products always contain alkyl or aryl azide. 1,4,5-Trialkyltetrazolium salts 94 undergo deprotonation under the action of sodium hydride in tetrahydrofuran.…”

2,2′‐Homocoupled Azine N,N′‐Dioxides or Azine N‐Oxides: CDC‐ or SNAr‐Controlled Chemoselectivity

“…A literature search on homocoupled 2,2′‐azine N ‐oxides revealed that they have been synthesized starting from azine N ‐oxides by (a) palladium‐catalysed coupling with halogenated azine (Scheme a), (b) coupling with 2‐pyridyllithium prepared from 2‐bromopyridine and tert ‐butyllithium at –78 °C (Scheme b) and (c) coupling with another molecule of azine N ‐oxide in the presence of an organocatalyst (Scheme c) . However, each of these reactions suffers from the limitations of a pre‐functionalized substrate, an expensive Pd catalyst, or drastic reaction conditions.…”