@article {42727, title = {Direct hydrogenation of amides to alcohols and amines under mild conditions}, journal = {Journal of the American Chemical Society}, volume = {132}, year = {2010}, month = {NOV}, pages = {16756{\textendash}16758}, abstract = {

The selective, direct hydrogenation of amides to the corresponding alcohols and amines with cleavage of the C-N bond was discovered. The expected products of C-O cleavage are not formed (except as traces in the case of anilides). The reaction proceeds under mild pressure and neutral, homogeneous conditions using a dearomatized, bipyridyl-based PNN Ru(II) pincer complex as a catalyst. The postulated mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core and does not involve hydrolytic cleavage of the amide. The simplicity, generality, and efficiency of this environmentally benign process make it attractive for the direct transformations of amides to alcohols and amines in good to excellent yields.

}, doi = {10.1021/ja1080019}, author = {Balaraman, Ekambaram and Gnanaprakasam, Boopathy and Shimon, Linda J. W. and Milstein, David} } @article {42720, title = {Synthesis of peptides and pyrazines from beta-aminoalcohols via extrusion of H2 catalyzed by ruthenium pincer complexes. ligand controlled selectivity}, journal = {Angewandte Chemie}, volume = {123}, year = {2011}, month = {OCT}, pages = {12448{\textendash}12452}, abstract = {

Bitte w{\"a}hlen: Die Wahl des Katalysators, eines Ru-Pinzettenkomplexes, bestimmt, ob Peptide oder Pyrazine aus β-Aminoalkoholen entstehen: Der PNN-Komplex 1 f{\"u}hrt, je nach Substituent R (siehe Schema), zu linearem Polyalanin oder zu cyclischen Dipeptiden, der PNP-Komplex 2 katalysiert die Bildung von Pyrazinen. Die Reaktionen finden in homogener L{\"o}sung unter neutralen Bedingungen statt.

}, doi = {10.1002/ange.201105876}, author = {Gnanaprakasam, Boopathy and Balaraman, Ekambaram and Ben-David, Yehoshoa and Milstein, David} } @article {42707, title = {Novel ruthenium complexes and their uses in processes for formation and/or hydrogenation of esters, amides and derivatives thereof}, number = {US 14/702,641}, year = {2012}, month = {OCT}, chapter = {US20150284417 A1}, abstract = {

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.

}, author = {Milstein, David and Balaraman, Ekambaram and Gunanathan, Chidambaram and Gnanaprakasam, Boopathy and Zhang, Jing} } @article {42712, title = {Ruthenium pincer-catalyzed cross-dehydrogenative coupling of primary alcohols with secondary alcohols under neutral conditions}, journal = {Advanced Synthesis \& Catalysis}, volume = {354}, year = {2012}, month = {SEP}, pages = {2403{\textendash}2406}, abstract = {

Cross-dehydrogenative coupling of primary alcohols with secondary alcohols to obtain mixed esters with the liberation of molecular hydrogen is achieved in high yield and good selectivity under neutral conditions, using a bipyridyl-based PNN ruthenium(II) pincer catalyst.

}, doi = {10.1002/adsc.201200438}, author = {Srimani, Dipankar and Balaraman, Ekambaram and Gnanaprakasam, Boopathy and Ben-David, Yehoshoa and Milstein, David} } @article {42710, title = {Synthesis of polyamides from diols and diamines with liberation of H2}, journal = {Journal of Polymer Science Part A: Polymer Chemistry}, volume = {50}, year = {2012}, month = {MAY}, pages = {1755{\textendash}1765}, abstract = {

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. {\textcopyright} 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

}, doi = {10.1002/pola.25943}, author = {Gnanaprakasam, Boopathy and Balaraman, Ekambaram and Gunanathan, Chidambaram and Milstein, David} } @article {42709, title = {Use of ruthenium complexes for formation and/or hydrogenation of amides and related carboxylic acid derivatives}, number = {US 13/471,037}, year = {2012}, month = {MAR}, type = {Grant}, chapter = {US9290441 B2}, abstract = {

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.

}, author = {Milstein, David and Gunanathan, Chidambaram and Ben-David, Yehoshoa and Balaraman, Ekambaram and Gnanaprakasam, Boopathy and Zhang, Jing} } @article {46278, title = {MnO2@Fe3O4 Magnetic Nanoparticles as Efficient and Recyclable Heterogeneous Catalyst for Benzylic sp(3) C-H Oxidation}, journal = {Chemistry-An Asian Journal}, year = {2019}, month = {SEP}, type = {Article}, abstract = {

Herein, we report a highly chemoselective and efficient heterogeneous MnO2@Fe3O4 MNP catalyst for the oxidation of benzylic sp(3) C-H group of ethers using TBHP as a green oxidant to afford ester derivatives in high yield under batch/continuous flow module. This catalyst was also effective for the benzylic sp(3) C-H group of methylene derivatives to furnish the ketone in high yield which can be easily integrated into continuous flow condition for scale up. The catalyst is fully characterized by spectroscopic techniques and it was found that 0.424 \% MnO2@Fe3O4 catalyzes the reaction; the magnetic nanoparticles of this catalyst could be easily recovered from the reaction mixture. The recovered catalyst was recycled for twelve cycles without any loss of the catalytic activity. The advantages of MnO2@Fe3O4 MNP are its catalytic activity, easy preparation, recovery, and recyclability, gram scale synthesis with a TOF of up to 14.93 h(-1) and low metal leaching during the reaction.

}, doi = {10.1002/asia.201900810}, author = {Pandey, Akanksha M. and Agalave, Sandip G. and Vinod, Chathakudath P. and Gnanaprakasam, Boopathy} } @article {48364, title = {Lewis acid-catalyzed chemodivergent and regiospecific reaction of phenols with quaternary peroxyoxindoles}, journal = {Journal of Organic Chemistry}, volume = {87}, year = {2022}, month = {NOV }, pages = {14155-14167}, type = {Article}, abstract = {

The indium-catalyzed regiospecific coupling of substituted phenol derivatives and quaternary peroxyoxindoles for the synthesis of C2 or C4 benzoxazin-3-one-substituted phenols via skeletal rearrangement is described. This reaction is demonstrated with 17 examples with good yields and diverse aryl substituents. In contrast to the indium-catalyzed reaction, the Cu(OTf)2- catalyzed reaction of the phenol with quaternary peroxyoxindoles afforded C2 or C4 2-oxindole-substituted phenol derivatives. This diverse catalytic reaction generated various biologically important phenol-substituted 2-oxindole derivatives directly without any skeleton rearrangement and was demonstrated with 19 examples in high yield. The regiospecificity and the reaction pathways were explained with the support of density functional theory (DFT).

}, issn = {0022-3263}, doi = {10.1021/acs.joc.2c01701}, author = {Shaikh, Moseen A. and Samal, Pragnya Paramita and Ubale, Akash S. and Krishnamurty, Sailaja and Gnanaprakasam, Boopathy} } @article {48678, title = {Catalyst-assisted selective vinylation and methylallylation of a quaternary carbon center using tert-butyl acetate}, journal = {Journal of Organic Chemistry}, volume = {88}, year = {2023}, month = {JUL}, pages = {9686-9703}, type = {Article}, abstract = {

The In-(OTf)(3)-catalyzed \& alpha;-vinylationof varioushydroxy-functionalized quaternary carbon centers using in situ generatedisobutylene from tert-butyl acetate is presentedas a novel synthetic methodology. Moreover, tert-butylacetate is a nonflammable feed stock and is a readily available sourcefor the in situ production of vinyl substituents, as demonstratedby the vinylation reaction with quaternary hydroxy/methoxy compounds.Moreover, an excellent selectivity for methylallylation over vinylationwas obtained with Ni-(OTf)(2) as a catalyst. In the case ofperoxyoxindole, methylallyl-functionalized 1,4-benzoxazin-3-one derivativeswere formed through the sequential rearrangement of peroxyoxindolefollowed by the nucleophilic attack by isobutylene. The detailed mechanismfor this reaction and rationalization for the selectivity are providedusing kinetics and density functional theory studies.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.2c03072}, author = {Mohanta, Nirmala and Samal, Pragnya Paramita and Pandey, Akanksha M. and Mondal, Shankhajit and Krishnamurty, Sailaja and Gnanaprakasam, Boopathy} } @article {48266, title = {FeCl2-catalyzed rearrangement of aryl peroxyoxindole into 1,3-benzooxazin-4-One}, journal = {Advanced Synthesis \& Catalysis}, volume = {365}, year = {2023}, month = {FEB}, pages = {515-521}, type = {Article}, abstract = {

We report an FeCl2-catalyzed radical rearrangement of aryl peroxyoxindoles into 1,3-benzooxazin-2-ones to obtain a variety of aryl substituted 1,3-benzooxazin-4-ones in moderate to good yields. Mechanistically, this skeletal rearrangement of peroxyoxindoles proceeded via radical pathway and was well supported with a series of experimental findings and DFT studies.

}, keywords = {1, 3-Benzooxazin-4-one, FeCl2, Peroxyoxindole, rearrangement, Ring expansion}, issn = {1615-4150}, doi = {10.1002/adsc.202201308}, author = {Mohanta, Nirmala and Samal, PragnyaParamita and Krishnamurty, Sailaja and Gnanaprakasam, Boopathy} }