Methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate

In the title compound, C11H11N3O2, prepared by the [3+2] cycloaddition reaction of benzyl azide with methyl propiolate, the dihedral angle between the ring planes is 67.87 (11)°.

In the title compound, C 11 H 11 N 3 O 2 , prepared by the [3+2] cycloaddition reaction of benzyl azide with methyl propiolate, the dihedral angle between the ring planes is 67.87 (11) .

Comment
Catalytic transformations of organic alkynes mediated by ruthenium complexes are well known, and confirmation for the intermediacy of ruthenium(II) acetylide and vinylidene complexes has been provided (Bruneau & Dixneuf, 1999;Cheng et al., 2009;Naota et al., 1998;Trost et al., 2001). Therefore, ruthenium was a logical choice in our search for a new catalyst of click reaction (Chen et al., 2009). Organic azides are synthetically useful reagents. Amongst many reactions, perhaps the most significant are the 1,3-dipolar cycloaddition reactions with alkynes to synthesize triazoles (Padwa, 1976). Triazoles are nitrogen heteroarenes which have found a range of important applications in the pharmaceutical and agricultural industries (Krivopalov & Shkurko, 2005).
A mixture of benzyl azide and methyl propiolate (1:1.5 equiv, respectively) in toluene was refluxed for 24 h in the presence of 5% moles of {(Tp)(PPh 3 ) 2 Ru(N 3 )}, leading to the title compound [Tp is hydridotris(pyrazolyl)borate]. Single crystals of the title compound suitable for X-ray structure analysis were obtained by recrystallization of the crude product from dichloromethane-ether.
In the title compound ( Fig. 1), phenyl and triazole are linked together through a methylene group. Of major interest is the methylene C atom, which presents a C-CH 2 -N angle of 112.13 (11)°, larger than the ideal tetrahedral value of 109.47°.

Experimental
A mixture of benzyl azide, methyl propiolate and {(Tp)(PPh 3 ) 2 Ru(N 3 )} in toluene was refluxed for 24 h. The solvent was removed under vacuum and the product was purified by silica gel chromatography. The unreacted alkyne and traces of side products were first eluted out with ether. The pure 1,4-disubstituted triazole product was then obtained by elution with CH 2 Cl 2 .

Refinement
H atoms were placed in idealized positions and constrained to ride on their parent atoms, with C-H = 0.95-0.99 Å and U iso (H) = 1.2 U eq (C) or U iso (H) = 1.5U eq (C). Fig. 1. Molecular structure of the title compound with labelling and displacement ellipsoids drawn at the 30% probability level (H atoms are shown as spheres of arbitrary radius).  (4)