Metal–Ligand Cooperation in the Catalytic Dehydrogenative Coupling (DHC) of Polyalcohols to Carboxylic Acid Derivatives

Abstract

Several polyols, which are easily available from sugars through biochemical conversion or hydrogenolytic cleavage, are directly converted into carboxylic acids and amides. This efficient dehydrogenative coupling process, catalyzed by a rhodium(I) diolefin amido complex, is an attractive approach for the production of organic fine chemicals from renewable resources. This method tolerates the presence of several hydroxy groups and can be extended to the direct synthesis of lactams from the corresponding amino alcohols under mild conditions.

C‐Alkylation of Ketones and Related Compounds by Alcohols: Transition‐Metal‐Catalyzed Dehydrogenation

“…[107] Ther eactions proceeded with 2-5 mol %Pd(OAc) 2 as the catalyst under mild reaction conditions,thus giving the desired ester products in moderate to good yields,with water formed as the only by-product. The homocoupling (self-esterification) of different benzyl and heterobenzyl alcohols was also realized to give the corresponding benzoate esters in 60-85 %yields.With water as the oxygen source,e ither ruthenium(II)- [109] or rhodium(I)-catalyzed [110] selective oxidation of alcohols in the presence of abase afforded the carboxylic acid salts [Eq. (36)].…”

Phosphine Ligand‐Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions

“…Among various homogeneous transition metal catalysts, Ru-complexes are the most efficient reported to date. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][60][61][62][63] Metal-ligand cooperative catalysis [64][65][66][67] can dramatically improve catalytic performance of ADC reactions using pincer ligands bearing NH, OH or CH 2 functionality. [40][41][42][43][44][68][69][70][71][72][73][74][75][76][77][78][79][80][81] Milstein, [40] Sun, [41] Yu, [42] Kundu [43] and Chen [44] have independently developed bifunctional Ru(II) catalysts for the synthesis of pyridine and quinoline derivatives (Scheme 1), b...…”

Regioselective modification of unprotected glycosides

“…In that way also methyl b-D-glucopyranoside could be oxidized selectively to the glucoronic acid (Scheme 15). 95 In contrast, the selective oxidation of the secondary hydroxy groups is extremely difficult and barely known. 2 Tsuda et al have described the selective oxidation of several methyl glycosides with stoichiometric bistributyltin oxide and bromine.…”