C–H⋅sO hydrogen bond networks in E- and Z-unsaturated esters of C-glycosides

Abstract

Methyl E(Z)-4,7 anhydro-5-benzamido-6,8-di-O-benzoyl-2,3,5-trideoxy-d-allo-oct-2-enoate have been synthesized like intermediates and isolated as single crystals during the synthesis of pyrazole-related C nucleosides as synthetic product with cytotoxic activity.1 Crystal structures of E(Z) isomers were determined by X-ray analysis. E isomer crystallizes in the triclinic crystal system, space group P1, a = 5.319(1) A, b = 10.758(2) A, c = 12.229(2) A, α = 72.38(2)∘, β = 89.97(2)∘, γ = 87.07(2)∘, D x = 1.320 Mgm−3 and Z isomer in the orthorhombic crystal system, space group P212121, a = 5.1297(13) A, b = 19.667(5) A, c = 25.871(6) A, D x = 1.348 Mgm−3. The molecular structure was solved by direct method on the basis of 2609 and 2727 unique reflections recorded at the temperature 293 K (E-isomer) and 173 K (Z-isomer) up to the final R-factor 0.0378 and 0.0435, respectively. C–H⋅sO contact networks were analyzed and the correlation established between the existence of the weak C–H⋅sO hydrogen bonds and the melting point of the single crystals.