Synthesis, characterization and catalytic properties of novel palladium(II) complexes containing aromatic sulfonamides: effective catalysts for the oxidation of benzyl alcohol

Abstract

In this article, N-(2-aminophenyl)arylsulfonamides (1-5) were successfully synthesized by the reaction of o-phenylenediamine and various benzenesulfonyl chlorides. The Schiff base derivatives (1a-f; 4e) of those compounds were obtained using different aldehydes. Then, a series of neutral-four coordinate Pd(II) complexes (6-10) were prepared from the reaction of Pd(OAc) 2 and 1-5. On the other hand, when we tried to synthesize Pd(II) complexes containing Schiff base/sulfonamide ligands, two different situations were observed. Generally, when an electron-donating group was attached to the imine fragment (1a-d) except for 1f, the Schiff base hydrolyzed and 6 was isolated. When an electron-withdrawing group was attached to the imine fragment (1e, 4e), neutral four-coordinate Pd(II) complexes (11-13) bearing Schiff base/sulfonamide ligands were isolated. The synthesized compounds were characterized by FT-IR, elemental analysis and NMR spectroscopy. The complexes were used as a catalyst in the oxidation reaction of benzyl alcohol to benzaldehyde in the presence of H 5 IO 6 in acetonitrile. All complexes showed satisfactory catalytic activity. The highest catalytic activity was obtained with 9.A solution of 1-5 (0.50 mmol) in DMSO (2 ml) was added to a solution of Pd(OAc) 2 (0.25 mmol) in DMSO(2 ml) in a Schlenk tube. The reaction mixture was stirred and heated at 70 C for 12 h, and then cooled. The volatiles were removed under reduced pressure. The residue was washed with diethyl ether (20 ml) and dried under vacuum. Data for Compounds 6-10Compound 6 Color brown; yield 73%; m.p. 300-301 C (dec.). 1 H NMR (DMSO-d 6 , d ppm): 6.55 (s, 4H, -NH 2 ), 6.68-6.74 (m, 2H, -H 1,3 ), 6.90 (t, 2H, J = 8 Hz, -H 2 ), 7.03 (d, 2H, J = 8 Hz, -H 4 ), 7.41-7.96 (m, 10H, -H x-z ),

Copper‐ and Phosphane‐Free Sonogashira Coupling of Arenediazonium o‐Benzenedisulfonimides

“…Interestingly, Pd complexes containing structures similar to 2 have previously been used as catalysts. Kalaycioglu et al8a prepared a series of neutral four‐coordinate palladium(II) complexes 9 (Figure 3) from Pd(OAc) 2 and N ‐(2‐aminophenyl)arylsulfonamides in DMSO. These complexes were used as catalysts in some oxidation reactions.…”

Hydrogenation and Redox Isomerization of Allylic Alcohols Catalyzed by a New Water-Soluble Pd–tetrahydrosalen Complex

“…In addition, their fluorescent properties can be utilized for analytical and imaging purposes . In particular, Schiff base complexes of palladium proved to be active catalysts for hydrogenation and oxidation and in various C–C coupling reactions …”

One‐pot stepwise reductive amination reaction by N‐coordinate sulfonamido‐functionalized Ru(II) complexes in water

“…Pure reactants and solvents were used at all stages of synthesis of the N ‐arenesulfonyl‐ o ‐phenylenediamine derivatives. Synthesis procedure of N ‐arenesulfonyl‐ o ‐phenylenediamines was modified from other synthesis methods of similar materials in the literature …”

“…Compounds 1 – 5 were synthesized and their data examined in previous fieldwork by our working partners . The data for compound 6 are presented herein.…”

“…Ruthenium, which has many advantages when used as a catalyst, has wide coordination patterns (Ru–arenes, N‐coordinate Ru, Ru–N‐heterocyclic carbenes, etc.) . Thus, it can easily be linked to different functional groups and inspire various economic processes …”