Ligand coordination sphere effect of Schiff base cis‐dioxomolybdenum(VI) complexes in selective catalytic oxidation of alcohols

Abstract

Several cis‐dioxomolybdenum(VI) complexes with Schiff bases‐derived ligands were synthesized and fully characterized. The catalytic performances of these complexes were tested in the alcohol oxidation under solvent‐free condition using H2O2 as oxidant giving high results. The influence of the oxygen, sulfur, and nitrogen atom within the coordination sphere around the molybdenum center was studied (S > N > O). From this study, we suggest that there exists a relationship between the electronegativity of the atom and the catalytic performance in alcohol oxidation.

Selective synthesis of 2‐substituted 2,3‐dihydroquinazolin‐4(1H)‐ones and quinazolin‐4(3H)‐ones catalyzed by Schiff base dioxomolybdenum(VI) complex

“…Different routes for quinazolin-4(3H)-ones synthesis liquid, 30,31 or as catalysts; for instance, Schiff base molybdenum(VI) complexes have been successfully used to catalyze olefins epoxidation, [32][33][34] sulfides 35 and alcohols oxidation. 36 Concerning molybdenum compounds for the synthesis of quinazolinones, Mo(CO) 6 was reported to promote the reaction as "CO" source but not as catalyst, also molybdenum doped ZnO was used as catalyst for the synthesis of quinazolinones. 37 As far as we know, there is no report using Schiff base molybdenum complexes as catalyst to synthesize quinazolin-4(3H)-ones or 2,3-dihydroquinazolin-4(1H)-ones.…”

“…Schiff bases compounds have been widely used, for example as adsorbents to remove heave metal ions from liquid, 30,31 or as catalysts; for instance, Schiff base molybdenum(VI) complexes have been successfully used to catalyze olefins epoxidation, 32–34 sulfides 35 and alcohols oxidation 36 . Concerning molybdenum compounds for the synthesis of quinazolinones, Mo(CO) 6 was reported to promote the reaction as “CO” source but not as catalyst, also molybdenum doped ZnO was used as catalyst for the synthesis of quinazolinones 37 .…”

The synthesis, structure, and catalytic properties of Cl‐substituted tridentate ONO Schiff base molybdenum(VI) complexes: Expeditious synthesis of 1,8‐dioxo‐octahydro‐xanthene derivatives

“…Schiff base compounds have shown to be water and pH-stable 20,21 for absorption, and are expected to work well in similar conditions for catalysis. Indeed, Schiff base molybdenum complexes have been used to catalyze the synthesis of organic compounds, such as epoxidation of olefins, 22,23 sulfides oxidation, 24 alcohols oxidation, 25 and preparation of quinazolin-ones, 26 pyrrole-2-ones, 27 and pyrazole derivatives. 28 Although the electrochemical behavior of dioxomolybdenum-based complexes has been studied in the early 1980s, 29,30 the role of the electronic density distribution along the ligands and their influence in the catalytic reactions is still under investigation.…”

“…Schiff base compounds have shown to be water and pH‐stable 20,21 for absorption, and are expected to work well in similar conditions for catalysis. Indeed, Schiff base molybdenum complexes have been used to catalyze the synthesis of organic compounds, such as epoxidation of olefins, 22,23 sulfides oxidation, 24 alcohols oxidation, 25 and preparation of quinazolin‐ones, 26 pyrrole‐2‐ones, 27 and pyrazole derivatives 28 …”

Schiff base Mo(vi) complexes grafted on Merrifield resin as recyclable and efficient catalysts for the synthesis of pyrrole-2-ones

“…37 In our previous work, Schiff base compounds have shown excellent high temperature and pH tolerance as adsorbents for Cd ion removal. 38,39 Furthermore, Schiff base molybdenum complexes displayed good catalytic activities for olefin epoxidation, 40–43 alcohol oxidation 44,45 and quinazolin-one synthesis. 46 In order to continue our research, we tried to promote the synthesis of pyrrole-2-ones through a multicomponent one-pot reaction using aromatic amines, aldehydes and ethyl pyruvate with Merrifield resin supported Schiff base molybdenum complexes as highly efficient catalysts (Scheme 1).…”