ABSTRACT
BACKGROUND: In this current work, a new synthesis strategy was developed to obtain 1,3,4-trisubstituted pyrazoles derivatives. METHODS: A series of 1,3,4-trisubstituted pyrazoles have been prepared via 1,3-dipolar cycloaddition reaction of 3-phenylsydnones with a variety of alkenes derivatives, symmetric and non-symmetric alkynes derivatives, N-phenyl-maleimide, N-benzylmaleimides, and maleic anhydride under conventional manner. RESULTS: Moreover, in this work, it has been demonstrated that the 4-bromopyrazole intermediates can be further functionalized by a combination of Suzuki-Miyaura crosscoupling reactions with aryl-boronic acids and N-arylation reactions of anilines. CONCLUSION: In summary, we have developed a new method to obtain 1,3,4 triarylated pyrazoles through 3-phenylsydnone 1,3-dipolar cycloadditions. By comparing the different reactions, it is apparent that high temperatures and xylene as solvent are key to achieving pyrazoles derivatives. The best yields were observed for symmetric and non-symmetric alkynes as dipolarophiles.
ABSTRACT
A new quinoline-based hydrazone, C16H12ClN3, was synthesized by a condensation reaction of 2-chloro-3-formyl-quinoline with phenyl-hydrazine. The quinoline ring system is essentially planar (r.m.s. deviation = 0.012â Å), and forms a dihedral angle of 8.46â (10)° with the phenyl ring. The mol-ecule adopts an E configuration with respect to the central C=N bond. In the crystal, mol-ecules are linked by a C-Hâ¯π-phenyl inter-action, forming zigzag chains propagating along the [10] direction. The N-H hydrogen atom does not participate in hydrogen bonding but is directed towards the phenyl ring of an adjacent mol-ecule, so linking the chains via weak N-Hâ¯π inter-actions to form of a three-dimensional structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from Hâ¯H (35.5%), Câ¯H/Hâ¯C (33.7%), Clâ¯H/Hâ¯Cl (12.3%), Nâ¯H/Hâ¯N (9.5%) contacts.
