02120nas a2200289 4500008004100000020004100041022001400082245007300096210006900169260026000238300001000498490000700508520099400515653001101509653001901520653001101539653001301550653001801563653002901581653002101610653001401631100002501645700002001670700001601690700002001706856010401726 2014 eng d a978-3-319-08482-4; 978-3-319-08481-7 a1436-600200aHydrogenation of polar bonds catalysed by ruthenium-pincer complexes0 aHydrogenation of polar bonds catalysed by rutheniumpincer comple aHEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANYbIEEE Commun Soc; IEEE Syst Man & Cybernet Soc; Galgotias Coll Engn & Technol; Hochschule Offenburg Univ Appl Sci; Int Neural Network Soc; India Chapter & Res Publishing Serv; Madhyam; WizIQ; ICACCI; IEEEcMAR a19-430 v483 a

Catalytic hydrogenation of polar bonds using molecular hydrogen is an important, atom-economical synthetic reaction. Classical reduction methods of polar bond often require reactive metal-hydride reagents in stoichiometric amount and produce copious waste. Hydrogenation of carbonyl compounds in particular provides `green' approaches to synthetically important building blocks, such as alcohols and amines. We have designed and synthesized several ruthenium-based pincer catalysts for unprecedented hydrogenation reactions including: (1) amides to alcohols and amines, (2) biomass-derived di-esters to 1,2-diols and (3) CO2 and CO derivatives to methanol. These atom-economical reactions operate under neutral, homogeneous conditions, at mild temperatures, mild hydrogen pressures, and can operate in absence of solvent with no generation of waste. The postulated mechanisms involve metal-ligand cooperation (MLC) by aromatization-dearomatization of the heteroaromatic pincer core.

10aAmides10aCarbon dioxide10aEsters10aHydrogen10aHydrogenation10aMetal-ligand cooperation10aPincer complexes10aruthenium1 aBalaraman, Ekambaram1 aMilstein, David1 aBruneau, C.1 aDixneuf, P., H. uhttps://library.ncl.res.in/content/hydrogenation-polar-bonds-catalysed-ruthenium-pincer-complexes-001801nas a2200253 4500008004100000022001400041245012100055210007100176260000800247300001400255490000800269520091600277653001001193653002301203653002101226653002501247653001401272653002901286100002301315700002101338700002401359700002001383856014401403 2024 eng d a1615-415000aManganese-catalyzed chemoselective direct hydrogenation of α,β-epoxy ketones and α-ketoamides at room temperature0 aManganesecatalyzed chemoselective direct hydrogenation of αβepox cAUG a3338-33450 v3663 a

Chemoselective hydrogenation of alpha,beta-epoxy ketones and alpha-ketoamides is achieved at room temperature (25 degrees C) using 2.0 bar H-2 and a pincer-ligated Mn(I) catalyst that provides synthetically valuable alpha-hydroxy epoxides and alpha-hydroxy amides. This protocol applies to a wide range of alkyl- and aryl-substituted alpha,beta-epoxy ketones, including terpenes (alpha-ionone, nootkatone, and R-carvone)- and steroids (testosterone and progesterone)-derived epoxy ketones, and tolerates H-2 sensitive functionalities, such as halides, acetyl, nitrile, nitro, epoxide, alkenyl and alkynyl groups. Additionally, alpha-ketoamides bearing reducible functional groups, including acetyl and diazo benzene, were untouched under this protocol and selectively converted to alpha-hydroxy amides. A preliminary mechanistic study highlighted the metal-ligand cooperative H-2 activation process.

10aalpha10abeta-epoxy ketones10achemoselectivity10adirect hydrogenation10amanganese10aMetal-ligand cooperation1 aShabade, Anand, B.1 aSingh, Rahul, K.1 aGonnade, Rajesh, G.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/manganese-catalyzed-chemoselective-direct-hydrogenation-%CE%B1%CE%B2-epoxy-ketones-and-%CE%B1-ketoamides02047nas a2200205 4500008004100000022001400041245014200055210006900197260000800266490000700274520126400281653001301545653002901558653002901587653001101616653003501627100001901662700002001681856014001701 2024 eng d a0947-653900aNickel-catalyzed chemodivergent coupling of alcohols: efficient routes to access α,α-disubstituted ketones and α-substituted chalcones0 aNickelcatalyzed chemodivergent coupling of alcohols efficient ro cMAR0 v303 a

Chemodivergent (de)hydrogenative coupling of primary and secondary alcohols is achieved utilizing an inexpensive nickel catalyst, (6-OH-bpy)NiCl2. This protocol demonstrates the synthesis of branched carbonyl compounds, alpha,alpha-disubstituted ketones, and alpha-substituted chalcones via borrowing hydrogen strategy and acceptorless dehydrogenative coupling, respectively. A wide range of aryl-based secondary alcohols are coupled with various primary alcohols in this tandem dehydrogenation/hydrogenation reaction. The nickel catalyst, along with KOtBu or K2CO3, governed the selectivity for the formation of branched saturated ketones or chalcones. A preliminary mechanistic investigation confirms the reversible dehydrogenation of alcohols to carbonyls via metal-ligand cooperation (MLC) and the involvement of radical intermediates during the reaction. The chemodivergent nickel-catalyzed approach provides alpha,alpha-disubstituted ketones from aryl-substituted secondary alcohols and benzyl alcohols via the borrowing hydrogen (BH) strategy in the presence of KOtBu, whereas exclusively alpha-substituted chalcones were accomplished in the presence of mild base K2CO3 through an acceptorless dehydrogenative coupling (ADC) strategy. image

10aAlcohols10adehydrogenative coupling10aMetal-ligand cooperation10aNickel10asubstituted carbonyl compounds1 aBansal, Sadhna1 aPunji, Benudhar uhttps://library.ncl.res.in/content/nickel-catalyzed-chemodivergent-coupling-alcohols-efficient-routes-access-%CE%B1%CE%B1-disubstituted