Phenols can be efficiently reduced by sodium formate and Pd/C as the catalyst in water and in the presence of amines to give the corresponding cyclohexylamines. This reaction works at rt for 12 h or at 60 °C under microwave dielectric heating for 20 min. With the exception of aniline, primary, secondary amines, amino alcohols, and even amino acids can be used as nucleophiles. The reductive process is based on a sustainable hydrogen source and a catalyst that can be efficiently recovered and reused. The protocol was developed into a continuous-flow production of cyclohexylamines in gram scale achieving very efficient preliminary results (TON 32.7 and TOF 5.45 h(-1)).

Reductive amination can be carried in i-PrOH/H 2 O as hydrogen sources using commercially available iron carbonyl complexes. Inside an aqueous alkaline environment, a hydridocarboferrate is formed and its reducing potential is exploited for hydrogenation of the imine (or iminium ion) in situ obtained from aldehydes or ketones, and primary or secondary amines in almost equimolar ratio. This completely sustainable and hydrogen-free process proceeds at 100 °C using Fe 3 (CO) 12 as catalyst precursor under convectional heating while Fe 2 (CO) 9 gave better results when the reaction was carried out under MW dielectric heating. Either enolizable and not-enolizable aldehydes may be successfully employed in reactions with aliphatic and aromatic amines.

The hydroformylation remains the most applied industrial process to produce aldehydes. Much research has been devoted to developing new catalyst systems since aldehydes are highly desired. Supported metal catalyst complexes have drawn renewed attention due to an increased interest in benign and environmental processes. In this paper, NiXantphos has been immobilized on hyperbranched poly(aryleneoxindole) supports, different in linker, via a one-step post-functionalization. Two heterogeneous hyperbranched poly(aryleneoxindole) supported NiXantphos ligands were evaluated in the microwave assisted rhodium catalyzed hydroformylation of olefins. After selecting the best reaction conditions, a variety of functionalized olefins was successfully converted into the desired linear aldehydes working under milder conditions compared to known processes, in terms of syngas pressure (4.8 bar), temperature (75 °C) and reaction times (20 min). The increased activity might emanate from a positive dendritic effect unique to the dendritic nature of the support. Furthermore, the catalyst system was successfully

We report ap rocedure for the continuous-flow production of cyclohexanone from phenol on the basis of the use of sodium formate as ab iomass-derived sourceo fh ydrogen and Pd/C as an easily accessible catalyst system.T he reactionw orked in water at pH 12.0 at 90 8C. By setting ap acked reactor charged with the Pd/C catalyst (10 wt %) at af low rate of 0.5 mL min À1 , we achieved continuous-flow production of cyclohexanone in high yield with high selectivity and productivity.Phenols, mostly in their polymeric forms in lignin, are the second mostp revalent naturallyo ccurring structural units of renewable biomass on the planet, and they are regarded as possibly valuable materials derivingf rom biomass treatment. Indeed,r emoval of the functional groups presenti nl ignin yields simple aromatic compounds such as phenol,b enzene, toluene,a nd xylene.C onsequently,a pplicationo fp henolsa s commodity chemicals or substrates foru seful transformations is highly desirable. [1] Cyclohexanone is one of the main commoditieso ft he chemicali ndustry feeding the productiono fc aprolactam and adipic acid, whichi nt urn are transformed into Nylon 6, Nylon 6,6, and polyamide resin. [2] Large production of cyclohexanonei sb ased on either the oxidation of cyclohexane under Co catalysis or the partial hydrogenation of phenol in the presence of different transition-metal catalysts (Scheme1). In terms of ad ifferent approach startingf rom phenol, the industrial process towardc yclohexanone comprises an initial reductive step to access cyclohexanol, which is furtherd ehydrogenatedt oc yclohexanonei nahigh-temperature gas-phase Pd-or Pt-catalyzed process. To define milder and more energy efficient one-step processes, the use of selectiveh omogeneous and heterogeneous catalysts hasb een investigated in the liquid phase and has resulted in many successful examples mainly based on single or mixed Pd, [3] Pt, [4] Ru, [5] Rh, [6] andN i [7] catalysts on different supports. [8] Considering the commonly proposed mechanism for the hydrogenation of phenol on supported palladiumc atalysts, reductiono ccurs on the phenolate ion adsorbed on the support in proximity of the metal particles, which are responsible for the activation of hydrogen. The chemical strategy to reduce phenol selectively is based on controlling the desorption of cyclohexanone from the catalyst surface beforef urther hydrogenation leads to cyclohexanol. [9] The use of formic acid derivativesa sahydrogen sourcei n combination with ap alladium catalyst is ap romising, safe, and sustainable alternative to classic methods. Formates are stable and nontoxic, and they can be obtainedf rom the processing of biomass. [10] Formic acid derivatives have also been proposed as hydrogen-storage materials, as they are suitable for safe transportation and handling. [11] Some examples of phenol reductionw ith the use of formic acid, [12] sodium formate, [13,14] and potassium formate [15] under batch conditions were reported recently.A lthough very attractive, some of these protocols feature ...

Domino Hydrogenation-Reductive Amination of Phenols, a Simple Process to Access Substituted Cyclohexylamines. -The reaction can also be conducted under thermal conditions (not shown) and is mentioned to be amenable to a continuous-flow production of cyclohexylamines in gram scale. -(JUMDE, V. R.; PETRICCI, E.; PETRUCCI, C.; SANTILLO, N.; TADDEI*, M.; VACCARO, L.; Org. Lett. 17 (2015) 16, 3990-3993, http://dx.doi.org/10.1021/acs.orglett.5b01842 ; Dip. Biotecnol, Chim. Farm., Univ. Studi Siena, I-53100 Siena, Italy; Eng.) -H. Haber