Reduced 3,4'-bi-pyrazoles carrying thio-phene and thia-zole substituents: structures of two intermediates and two products.

Cyclo-addition reactions between 3-(5-ar-yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(thio-phen-2-yl)prop-2-en-1-ones and thio-semicarbazide leads to the formation of reduced 3,4'-bi-pyrazole-2-carbo-thio-amides. Further cyclo-addition of these inter-mediates with either diethyl acetyl-enedi-carboxyl-ate or 4-bromo-phenacyl bromide leads to reduced 3,4'-bi-pyrazoles carrying oxo-thia-zole or thia-zole substituents, respectively. The structures of two representative inter-mediates and two representative products established unambiguously the regiochemistry of the cyclo-addition reactions. The mol-ecules of 3'-methyl-5'-(2-methyl-phen-oxy)-1'-phenyl-5-(thio-phen-2-yl)-3,4-di-hydro-1'H,2H-3,4'-bi-pyra-zole-2-carbo-thio-amide, C25H23N5OS2 (Ia), are linked by N-H⋯N hydrogen bonds to form simple C(8) chains. The analogous compound 5'-(2,4-di-chloro-phen-oxy)-3'-methyl-1'-phenyl-5-(thio-phen-2-yl)-3,4-di-hydro-1'H,2H-3,4'-bi-pyra-zole-2-carbo-thio-amide hemihydrate crystallizes as a hemihydrate, C24H19Cl2N5OS2·0.5H2O (Ib), and the independent components are linked into a chain of spiro-fused R 4 4(20) rings by a combination of O-H⋯N and N-H⋯O hydrogen bonds. In the structure of ethyl (Z)-2-{2-[3'-methyl-1'-phenyl-5-(thio-phen-2-yl)-5'-(2-methyl-phen-oxy)-3,4-di-hydro-1'H,2H-3,4'-bi-pyrazole-2-yl]-4-oxo-4,5-di-hydro-thia-zol-5-yl-idene}acetate, C31H27N5O4S2 (II), inversion-related pairs of mol-ecules are linked by paired C-H⋯π(arene) hydrogen bonds to form cyclic centrosymmetric dimers, but there are no direction-specific inter-molecular inter-actions in 4-(4-bromo-phen-yl)-2-[5'-(2,4-di-chloro-phen-oxy)-3'-methyl-1'-phenyl-5-(thio-phen-2-yl)-3,4-di-hydro-1'H,2H-3,4'-bi-pyrazole-2-yl]-4-thia-zole, C32H22BrCl2N5OS2 (III). Comparisons are made with the structures of some related compounds. © Harish Chinthal et al. 2021.