N-amino azoles

The N-aminopyrroles 9-16 were obtained from these amides in 80-95% yield by alkahne hydrolysis (1-36 h) with a KOH saturated refluxing ethylene glycol solution. This convenient but rather drastic deprotection protocol shows that N-ami -nopyrroles are quite stable compounds. The high stabihty of aminopyrroles 9-16 presumably results from fhe fact fhat both a-positions are blocked in fhese 2,5-di-substituted pyrroles. The parent member of this family of compounds, unsubstituted N-aminopyrrole, is fhe only commercially available N-amino-azole. Ironically, it is also fhe least stable compound in the series. 

Thus eleven N-amino-N-heterocycles were synfhesized. Together with the commercially available unsubstituted N-amino-pyrrole, twelve different N-amino-azoles became available as ligand precursor. Their properties - with regard of their intended use as steering groups in the ligand backbone of the olefin polymerization catalysts - differ in terms of steric bulk of the substituents, symmetry, and electronic properties, as can be seen from inspecting Chart 3.1. 

Retrosynthetically, preparation of N-azolyl 2,6-bis(imino)pyridyl metal complexes as precatalysts for polymerization involves (i) synthesis of N-amino azoles, (ii) condensation of 2,6-diacetylpyridine with two equivalents of N-amino azole, and (iii) complexation of die appropriate transition metal halide with the terdentate ligands. The latter two reactions present no real challenge and are more or less analogous to fhe published preparation of N-aryl 2,6-bis(imino)pyridyl complexes [13], and fhe more demanding synthesis of N-amino-azoles was covered in a preceding section. 

The resulting triazoles can be N-alkylated by treatment with alkyl halides (0.25 mol/L, 30 equiv., DMF, NaOH), but mixtures of the 1-alkylated and 2-alkylated triazoles are obtained [255]. 1,2,4-Triazoles have also been prepared from N-amino-amidines (amidohydrazones Entry 4, Table 15.20), which were prepared from resin-bound thioamides by S-alkylation with methyl triflate followed by treatment with hydrazine [256]. 1,2,4-Tri azoles undergo Michael addition to polystyrene-bound a-acetamido acrylates to yield triazole-derived a-amino acids (Entry 7, Table 15.20). Benzotriazoles have been N-arylated on insoluble supports by treatment with aryl-boronic acids in the presence of catalytic amounts of copper salts (Entry 8, Table... 

Amination at an azole ring nitrogen is known for N-unsubstituted azoles. Thus, 1,2,3-triazole and 4,5-diphenyl-l,2,3-triazole with hydroxylamine-O-sulfonic acid give 1-amino 145 and 2-amino 146 derivatives in a ratio of 4 1 and 1 3, respectively. 3-Amino-5-/isy/-butylpyrazole affords 147 and indazole and tetrazole give comparable amounts of the 1- and 2-amino derivatives, and ethyl benzothiazol-2-ylcarboxylate reacts at room temperature <2001JOC8528>. Pyrazole is easily N-nitrated with nitrogen dioxide in the presence of ozone <1996JCR(S)388>. 

Epa OF N-AMINO and A-METHYL DERIVATIVES OF Some Condensed Azoles ... 

Nitrile molecules from 4-amino-l,2,4- Deamination of N-amino-N-triazoles. 4-Amino-3,5-diphenyl-l,2,4-tri- heterocyclics. N-Aminocarbazole azole... 

Substituted isoxazoles, pyrazoles and isothiazoles can exist in two tautomeric forms (139, 140 Z = 0, N or S Table 37). Amino compounds exist as such as expected, and so do the hydroxy compounds under most conditions. The stability of the OH forms of these 3-hydroxy-l,2-azoles is explained by the weakened basicity of the ring nitrogen atom in the 2-position due to the adjacent heteroatom at the 1-position and the oxygen substituent at the 3-position. This concentration of electron-withdrawing groups near the basic nitrogen atom causes these compounds to exist mainly in the OH form. 

Diazo coupling is expected to occur only with highly reactive systems, and experiment bears this out. Diazonium ions couple with the anions of N-unsubstituted imidazoles at the 2-position (e.g. 125 yields 126) and with indazoles (127) in the 3-position. In general, other azoles react only when they contain an amino, hydroxyl, or potential hydroxyl group, e.g. the 4-hydroxypyrazole (128), the triazolinone (129) and the thiazolidinedione (130) (all these reactions occur on the corresponding anions). 

If an aromatic o-diamine such as 1,2-diaminobenzene (2.24) is diazotized in dilute aqueous acid, the 2-aminobenzene-l-diazonium ion formed first (2.25) undergoes a rapid intramolecular N-azo coupling reaction to give 1,2,3-benzotri-azole (2.26). Both amino groups of 2.24 can, however, be diazotized in concentrated acid (Scheme 2-18), forming the bis-diazonium ion 2.27. 1,3- and 1,4-diamines must also be bisdiazotized in concentrated acids in order to avoid inter-molecular N- or C-coupling. 

Instead of the corresponding cyclized product, only the N-(, 2,4-thiadi-azol-3-yl)aminomethylenemalonate (1133) was obtained in 12% yield from the reaction of 3-amino-5-ethoxycarbonylamino-l,2,4-thiadiazole and EMME in polyphosphoric acid at 110°C for 3 hr (77JHC621). 

A high-nitrogen compd with the empirical formula C H N, mw 279.26, N 45.15%, is listed in Beil as 5-Amino-(4,y -azobenztri-azole) and its formula is given as ... 

Ethyl am ino-a-tetr azole or S Ethyl amino-IH-tetrazole, (C, Hs )HN C-NH-N, crysts,... 

Ami no-5-hydroxy-1,2,3-tri azole-4-carboxylic acid hydroxide or l-Amino-4-hydrazido-carbon-S hydroxytriazole,(Called 1-Amino-4-hydrazidocarbon-5-oxytriazol in Ref 2), HO C-N(NH ) N, mw 158.13, N... 

Aminomethoxyphenyltetrdzoles, Anisylctmino-tetr azoles or Anisidinotetrazoles,Ct,H9N50, mw 191.19) N 36.63%- The following isomers are described in the literature 5-Amino-l-(o-methoxyphenyl)-a(or lH)-tet-roxole or l-(2-Anisyl)-5-amino-tetrazole (o-CH,O.C6HJ... 

Amino-2-methyl- 3-tetrazole or 5-Amlno-2 me thyl-2H-tetr azole, H2N ( N-N-CH3. 

Ami no- 5-phenyl-a-tetr azole l-Amino-5 phenyl-1H-tetra zo I e or 5 Phenyl-l-amino-tetrazole, C HS-C-N(NH2 )-N. Crysts, mp... 

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