Water Soluble Single Sulfonamide, Ruthenium, Iridium Complex Catalytic Hydrogen Transfer Reaction Of Aromatic Aldehydes, Ketones

Alcohols are important chemicals, transfer hydrogenation reactions is a very practical and efficient synthetic tool to obtain these compounds. Water, as a green solvent used in hydrogen transfer reaction, while maintaining the catalytic activity, overcomeing the recycling problem of the catalyst in the homogeneous system, at the same time, reducing the costs, is a good response to the call of green chemistry and the sustainable development strategies.So, organic synthesis used water as solvent, has a broader industrial application prospects. In this paper, we aim at exploring the phase system catalytic activity of water-soluble monosulfonamide-Ru、Ir complexes in transfer hydrogenation reactions of aromatic aldehydes, ketones. This thesis consists of three parts:1、Six water-soluble analogues of (R,R)-N-(p-tolylsulfonyl)-1,2- diamino- cyclohexane, containing an additional quaternary ammonium group, have been synthesized. The ruthenium catalysts prepared in situ by reacting chiral mono- sulfonamides with [RuCl2(p-cymene)]2 afforded high conversion rates and enantiomeric excess (ee) values in the asymmetric transfer hydrogenation of aromatic ketones in aqueous HCOONa. The asymmetric transfer hydrogenation of acetophenone could complete in 2 hours, with the conversion of 99% and ee values of 84%. For other different substituted aromatic ketones catalyzed, we found that different substituents had little effect on the conversion, but the ee values showed a great difference, R1 or R2 was electron donating functional group, ee values were all lower, while R1 or R2 was electron pull functional group, ee values did not change significantly. Furthermore, the catalyst could be easily recoveredand reused at least five times without obviousloss of ee values.2、A polyethylene glycol-supported chiral monosulfonamide was synthesized from (R,R)-1,2-diaminocyclohexane and shown to act as a ligand for ruthenium(II)-catalyzed asymmetric transfer hydrogenation of aromatic ketones in neat water using sodium formate as the hydrogen source. Good enantioselectivities were obtained and the catalyst could be easily separated from the reaction mixture and reused several times. As the results shown, for various ketones, including 2-substituted, electron-rich and electron-deficient variants, the catalyst afforded quantitative conversion in 6 h reaction time. For the asymmetric transfer hydrogenation reaction of acetophenone, the conversion was excellent and the ee was good. For the asymmetric transfer hydrogenation reaction of propiophenone, the conversion was excellent but the ee was not comparable to that of acetophenone. Thus, as the steric bulkiness increased, the enantioselectivities decreased. The halo group on the 2-position slightly improved the enantioselectvity. 3、Water-soluble monosulfonamide ligands, containing an additional quaternary ammonium group, have been synthesized from 1,2- ethylenediamine, and their application in ruthenium and iridium-catalyzed transfer hydrogenation of aldehydes are described. Various aldehydes, including electron-deficient and electron-rich variants, were reduced with high conversions and chemoselectivity using sodium formate as a hydrogen source in neat water.