2‐Alkyl‐1,2,3,4‐benzotetrazinium Tetrafluoroborates: Their Reaction with Nucleophiles

Abstract

Hindered chiral ethers with one or two stereocenters are now readily available by allylic etherification of primary and secondary alkoxides (see reaction). When an Ir–phosphoramidite complex is used as the catalyst, the reaction proceeds with high regio‐, enantio‐, and diastereoselectivity. Np=1‐naphthyl.

2-Alkyl-1,2,3,4-benzotetrazinium Salts: Synthesis and NMR Studies of the Novel 2-Alkyl-1,2,3,4-tetrazinium/ortho-(Alkylazo)diazonium Equilibrium

“…This shift is indicative of the tertbutyl group being directly attached to the positively charged N atom; similar chemical shifts were observed for the tertbutyl group of the related tetrazinium N-oxide salts D [R ϭ 6,8-Br 2 , δ H ϭ 2.08 ppm; δ C ϭ 28.0 (CH 3 ), 85.8 (CMe 3 ) ppm]. [4] On cooling of the sample of 4f from 297 to 263 K the 1 H and 13 C NMR signals were not shifted. In the 15 N NMR/INEPT spectra of 4f at 273 K, the nitrogen attached to the tert-butyl group was observed at δ N ϭ Ϫ134.1 ppm.…”

“…[2] Only annulated representatives of this class are available: triazolo-annulated 1,2,3,4-tetrazine [3] A, benzo-annulated 1,2,3,4-tetrazine 1-N-oxides [4] B, benzo-(C), and furazano-annulated 1,2,3,4-tetrazine 1,3-di-N-oxides, [5] and 2-alkyl-1,2,3,4-benzotetrazinium 4-N-oxide salts D. [4] 13 C NMR spectra. The equilibrium strongly depends on the substituents on the aromatic ring, while being practically unaffected by the substituents (methyl or tert-butyl) on the azo group.…”

Synthesis and tautomeric transformations of 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones

“…11 Diazotization of ortho (tert butylazo)anilines 1a-g with nitrosonium tetrafluoroborate gave the correspond ing ortho (tert butylazo)phenyldiazonium tetrafluoro borates 2a-g (see Ref. 12).…”

Release of Nitrosating Species in the Course of Reduction of Benzo-1,2,3,4-tetrazine 1,3-Dioxides

“…Interestingly, the reduction of BTDOs does not involve the intermediate formation of benzo-1,2,3,4-tetrazine 1-oxides (compound F in Scheme ). The decomposition of the latter compounds is known to proceed via ring-opening to afford ortho -azid o -nitroso-benzenes followed by evolution of the N 2 molecule to finally give benzofurazans, which were not observed in the reactions under investigation. These observations enable pathway 2 to be considered the most probable.…”