01850nas a2200181 4500008004100000245013700041210006900178260000800247300001400255490000600269520115100275100002501426700002801451700001601479700002501495700002001520856012801540 2011 eng d00aEfficient hydrogenation of organic carbonates, carbamates, and formates indicates alternative routes to methanol based on CO2 and CO0 aEfficient hydrogenation of organic carbonates carbamates and for cJUL a609–6140 v33 a

Catalytic hydrogenation of organic carbonates, carbamates and formates is of significant interest both conceptually and practically, because these compounds can be produced from CO2 and CO, and their mild hydrogenation can provide alternative, mild approaches to the indirect hydrogenation of CO2 and CO to methanol, an important fuel and synthetic building block. Here, we report for the first time catalytic hydrogenation of organic carbonates to alcohols, and carbamates to alcohols and amines. Unprecedented homogeneously catalysed hydrogenation of organic formates to methanol has also been accomplished. The reactions are efficiently catalysed by dearomatized PNN Ru(II) pincer complexes derived from pyridine- and bipyridine-based tridentate ligands. These atom-economical reactions proceed under neutral, homogeneous conditions, at mild temperatures and under mild hydrogen pressures, and can operate in the absence of solvent with no generation of waste, representing the ultimate ‘green’ reactions. A possible mechanism involves metal–ligand cooperation by aromatization–dearomatization of the heteroaromatic pincer core.

1 aBalaraman, Ekambaram1 aGunanathan, Chidambaram1 aZhang, Jing1 aShimon, Linda, J. W.1 aMilstein, David uhttps://library.ncl.res.in/content/efficient-hydrogenation-organic-carbonates-carbamates-and-formates-indicates-alternative01874nas a2200157 4500008004100000245013500041210006900176260000800245520121900253100002001472700002501492700002801517700002801545700001601573856012701589 2012 eng d00aNovel ruthenium complexes and their uses in processes for formation and/or hydrogenation of esters, amides and derivatives thereof0 aNovel ruthenium complexes and their uses in processes for format cOCT3 a

The present invention relates to novel Ruthenium complexes and related borohydride complexes, and their use for (1) hydrogenation of amides (including polyamides) to alcohols and amines; (2) preparing amides from alcohols with amines (including preparing polyamides (e.g., polypeptides) by reacting dialcohols and diamines or by polymerization of amino alcohols); (3) hydrogenation of esters to alcohols (including hydrogenation of cyclic esters (lactones), cyclic di-esters (di-lactones) or polyesters); (4) hydrogenation of organic carbonates (including polycarbonates) to alcohols and of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (5) dehydrogenative coupling of alcohols to esters; (6) hydrogenation of secondary alcohols to ketones; (7) amidation of esters (synthesis of amides from esters and amines); (8) acylation of alcohols using esters; (9) coupling of alcohols with water to form carboxylic acids; and (10) dehydrogenation of beta-amino alcohols to form pyrazines. The present invention further relates to novel uses of certain pyridine Ruthenium complexes.

1 aMilstein, David1 aBalaraman, Ekambaram1 aGunanathan, Chidambaram1 aGnanaprakasam, Boopathy1 aZhang, Jing uhttps://library.ncl.res.in/content/novel-ruthenium-complexes-and-their-uses-processes-formation-andor-hydrogenation-esters02002nas a2200169 4500008004100000245007400041210006900115260000800184300001600192490000700208520142300215100002801638700002501666700002801691700002001719856009301739 2012 eng d00aSynthesis of polyamides from diols and diamines with liberation of H20 aSynthesis of polyamides from diols and diamines with liberation  cMAY a1755–17650 v503 a

The amidation reaction based on catalytic coupling of alcohols with amines previously reported by us, using the pincer complexes 1 and 2 as catalysts, was applied to the generation of polyamides from nonactivated diols and diamines. A range of polymers was prepared, with Mn up to 26.9 kDa. Unlike the traditional syntheses of polyamides based on carboxylic acid derivatives, which require the use of toxic reagents and generate stoichiometric amounts of waste, this process generates only molecular hydrogen as byproduct. Both aromatic and aliphatic diols and diamines were used. Gel permeation chromatography measurements of the dimethylformamide-soluble polymers and thermal studies of the polyamides were performed. Matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) spectra are also reported. Thermogravimetric analyses studies indicate that the aromatic polyamides (with the exception of the pyridine-based polyamide) are more thermally stable than the aliphatic ones. This general, environmentally benign method for the synthesis of polyamides is homogeneously catalyzed under neutral conditions by dearomatized ruthenium-pincer complexes 1 and 2 and proceeds in 1,4-dioxane under an inert atmosphere. Conditions for polyamidation in the absence of solvent are also reported, using the pincer complex 2 as catalyst. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

1 aGnanaprakasam, Boopathy1 aBalaraman, Ekambaram1 aGunanathan, Chidambaram1 aMilstein, David uhttps://library.ncl.res.in/content/synthesis-polyamides-diols-and-diamines-liberation-h201646nas a2200169 4500008004100000245011600041210006900157260000800226520097300234100002001207700002801227700002401255700002501279700002801304700001601332856012801348 2012 eng d00aUse of ruthenium complexes for formation and/or hydrogenation of amides and related carboxylic acid derivatives0 aUse of ruthenium complexes for formation andor hydrogenation of  cMAR3 a

A process for preparing amides by reacting a primary amine and a primary alcohol in the presence of a Ruthenium complex to generate the amide and molecular hydrogen. Primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only byproduct) in high yields and high turnover numbers. Also disclosed are processes for hydrogenation of amides to alcohols and amines; hydrogenation of organic carbonates to alcohols; hydrogenation of carbamates or urea derivatives to alcohols and amines; amidation of esters; acylation of alcohols using esters; coupling of alcohols with water and a base to form carboxylic acids; dehydrogenation of beta-amino alcohols to form pyrazines and cyclic dipeptides; and dehydrogenation of secondary alcohols to ketones. These reactions are catalyzed by a Ruthenium complex which is based on a dearomatized PNN-type ligand of formula A1 or precursors thereof of formulae A2 or A3.

1 aMilstein, David1 aGunanathan, Chidambaram1 aBen-David, Yehoshoa1 aBalaraman, Ekambaram1 aGnanaprakasam, Boopathy1 aZhang, Jing uhttps://library.ncl.res.in/content/use-ruthenium-complexes-formation-andor-hydrogenation-amides-and-related-carboxylic-acid