4-Aryl-1 -sulfonyl-1, 3-triazoles

The addition reactions of aryl azides onto enamines bearing a carbonyl, sulfonyl, or nitro group in the 0 position with respect to the nitrogen atom have been investigated by Italian authors.240-241 The expected triazoline derivatives could not be isolated but were immediately converted into the corresponding 1,2,3-triazoles (49) and secondary amines. The reaction of p-nitrophenyl azide with l-benzoyl-2-morpholino-l-propene (48) is given as a typical example. 

Condensation of 2-amino-5-aryl-5//-thiazolo[4,3-6][I,2,4]oxadiazoles (93 X = 0) and -thia-diazoles (93 X = S) with formaldehyde and a-amino acids leads to 7-aryl-3-(carboxy-alkyl)thiazolo[3, 4 3,2][I,3,4]oxadiazoles (94 X = 0) and -thiadiazoles (94 X = S), respectively. Under the same reaction conditions 5-aryl-2-sulfonyl-l,5-dihydrothiazolo[3,4-Z)][l,2,4]triazoles (95) are converted into 7-aryl-3-(carboxyalkyl)thiazolo[3, 4 2,3][l,2,4]triazoles (96) (Equation (9)) <94MI 805-01 >. 

For the heterocondensation of 2-amino-5-aryl-5/f-thiazolo[4,3-6][l,2,4]oxadiazoles and -thia-diazoles (93) and 5-aryl-2-sulfonyl-l,5-dihydrothiazolo[3,4-Z ][l,2,4]triazoles (95) with formaldehyde and a-amino acids see Section 8.05.6.1.2 <94Mi 805-oi>. 

The reaction of 3-aryl-5-sulfonyl-4//[l,2,4]triazole with phenacyl bromides in methanol gives 3,5-diarylthiazolo[2,3-c][l,2,4]triazoles (46) in one step (see Section 8.05.9.1.11) (Equation (114)) <88CAT91>. 

On treatment with phosphorus pentasulfide 4-amino-5-sulfonyl-4//-[l,2,4]triazoles (107 R = 2-ArCONHC6H4) are converted into 6-aryl-3-(2-aminophenyl)[l,2,4]triazolo[3,4-i>][l,3,4]thiadiazoles (3). This conversion is presumed to involve the transformation of the amide into the thioamide and a subsequent transfer of the thioaroyl group from the phenylamino side chain to the A-amino... 

A-Sulfonylamidines can be prepared by three-component coupling [31] of alkynes (R = alkyl, aryl or silyl), sulfonyl azide and amine, which is known as click chemistry. [32] The use of alkyl azides in place of sulfonyl azide without a copper catalyst results in the formation of 1,2,3-triazoles (Scheme 3.18). This reaction shows substrate tolerance to each component. Reaction with an optically active amino ester is performed without racemiza-tion. A-Boc-ynamide (R = NPhBoc) can act as the alkyne component in the synthesis of N-Boc-aminoamidines [33]. 

Dimerization of 2-amino-3,4,6-tri-0-benzyl-2-deoxy-D-glucose with l.l -thionyl-or sulfonyl-di-imidazole gave the fructosazine and bis-tetrahydropyrano-piper-azine derivatives 73 and 74 in a ratio of 1 5, respectively a related compound appeared in Vol. 25, p.l32. The P-carboline derivative 75, isolated as a natural product from a hybrid plant cell culture product, was synthesized in six steps from tryptamine and ( )-4,5,6-tri-0-acetyl-2,3-dideoxy-D-ery/Aro-hex-2-enose. Thiazolo-triazoles such as 76, termed acyclo-C-nucleosides, were obtained on deacetylation of the product from condensation of peracetylated D-gluconic or galactaric acids with 4-araino-3-aryl-l,2,4-triazole-5-thiols in the presence of POCls. The related 1,2,4-triazole 77 and dihydroimidazole 78 were obtained by condensation of D-glucono-1,5-lactone with aminoguanidine and ethylenedia-mine, respectively, followed by acetylation then O-deacetylation. ... 

Apart from the utilization of aryl- and vinyl-diazoacetates that can achieve the moderate to high chemo-, regio-, and enantioselectivity in intermolecular asymmetric C—H bond insertion reactions, Af-sulfonyl-l,2,3-triazole 11 was found to be able to function as an alternative carbene precursor for diverse transformations (Scheme 1.4). One advantage for using the N-sulfonyl-1,2,3-triazole is that it could be easily prepared by the Cu -catalyzed azide-alkyne cycloaddition (CuAAC) reaction, and in some cases, delicately designed reactions can be conducted in a one-pot procedure starting from alkynes and sulfonyl azides. Moreover, since there exists an inherent equilibrium... 

The reaction of sulfonyl azides with terminal alkynes is an interesting exception. Whereas aryl and alkyl azides react with activated alkynes to give the corresponding 1,2,3-triazoles, intermediate sulfonyltriazoles result in the formation of different products. In the presence of amines, N-sulfonyl azides are converted to M-sulfonyl amidines, whereas under aqueous conditions, M-acylsulfonamides are the major products [76-78]. Nevertheless, Fokin et al. reported conditions for the successful formation of N -sulfonyl-1,2,3-triazoles 105 shown in Scheme 22 [79]. 

A rhodium synthesis of sulfenylated imines containing a quaternary centre has been reported through a denitrogenative [2,3]-sigmatropic rearrangement of 4-aryl-, 4-alkenyl-, and 4-alkyl-A-sulfonyl-l,2,3-triazoles with aryl (alkyl)allyl sulfides (Scheme 57)7 ... 

The first examples of a direct 1,5-substituents tetrazole synthesis via an intermolecular [2 + 3]-cycloaddition reaction of organic azides (based on the results for a similar synthesis of triazoles) were developed by Sharpless et al. in 2002 using sulfonyl or acyl cyaiudes (Scheme 9.8). In both cases, the Click reaction involved simple heating of the organic azides (hindered, aliphatic or aryl azides) and the nitriles into a homogenous liquid at higher reaction temperature (80-100 °C), in which no further purification was necessary. 

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