Synthesis and characterization of new 3,3`-bipyrazole-4,4`-dicarboxylic acid derivatives and some of their palladium(II) complexes as pre-catalyst for Suzuki coupling reaction in water

Abstract

The 1,3-dipolar cycloaddition reaction of bis-hydrazonyl chlorides with methyl propiolate afforded dimethyl 1,1¢-aryl-3,3`-bipyrazole-4,4`-dicarboxylates (5a,b). Heating the later compound 5a with a mixture of HCl/AcOH gave 3,3`-bipyrazole-5,5`-dicarboxylic acid derivative 6. Treatment of the hydrazonoyl chloride (1a) and 3,3`-bipyrazole-5,5`-dicarboxylic acid (6) with palladium(II) chloride gave the corresponding Pd-complexes 7 and 8, respectively. The catalytic activity of the prepared Pd-complexes was examined in the Suzuki cross-coupling reaction of phenylboronic acid with activated and deactivated aryl(hetaryl) bromides. The catalyst system provides very good to excellent yields, 85-94%. The structures of the obtained products were established from their elemental analysis, spectral data, XPS, EDX, and single crystal X-ray crystallography. Crystal data for C10H7N2O2 (6): triclinic, space group P-1 (no. 2), a = 3.9956(10) Å, b = 9.8917(18) Å, c = 10.810(3) Å, α = 94.167(15)°, β = 94.979(19)°, γ = 98.953(15)°, V = 418.83(16) Å3, Z = 2, T = 296.(2) K, μ(Cu Kα) = 0.887 mm-1, Dcalc = 1.484 g/cm3, 5469 reflections measured (11.72° ≤ 2Θ ≤ 133.24°), 1420 unique (Rint = 0.0633, Rsigma = 7.24%) which were used in all calculations. The final R1 was 0.1055 (>2sigma(I)) and wR2 was 0.3620 (all data).

Synthetic Routes to Bioactive Bipyrazole Derivatives

“…Treatment of 3,3′‐bipyrazole‐5,5′‐dicarboxylic acid 43 with a solution of palladium(II) chloride in methanol furnished the Pd(II)‐complex 46 in 63 % yield. The 3,3′‐bipyrazole‐based Pd(II)‐complex 46 was employed as a good catalyst for Suzuki C−C cross‐coupling reactions [51,52] …”

“…The 3,3'-bipyrazole-based Pd(II)complex 46 was employed as a good catalyst for Suzuki CÀ C cross-coupling reactions. [51,52] Double 1,3-dipolar cycloaddition reaction of the bisnitrilimine 38 A with two equivalents of 2-arylidene-1-benzosuberone derivatives 47 was reported to give the bis-[1',4'-diaryl-1-oxo-spiro-benzosuberane-2,5'-pyrazoline] derivatives 48 (Scheme 8). The reaction was carried out under both thermal heating (at reflux for 36 h) as well as ultrasonic irradiation conditions (at 70°C for 3 h) in ethanol in the presence of triethylamine.…”

Theoretical DFT study of Cannizzaro reaction mechanism: A mini perspective

“…Kinetics is an important aspect of any reaction; especially for organic reactions [11][12][13][14][15]. The kinetics give us important data about the reaction.…”