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Several di- and triarylfuran derivatives were prepared in high yields from but-2-ene-1,4-diones/but-2-yne-1,4-diones using formic acid in the presence of a catalytic amount of palladium on carbon and in poly(ethylene glycol)-200 medium in a one-pot operation under microwave irradiation (1-5 min).

Stille couplings catalyzed by palladium-on-carbon with CuI as a cocatalyst: Synthesis of 2-(4′-acetylphenyl)thiophene1 product: 2-(4′-acetylphenyl)thiophene Keywords: coupling; metal-catalyzed reactions, copper; metal-catalyzed reactions, palladium

[reaction: see text] A new a versatile catalyst for hydrogenation reactions wherein palladium on carbon is encapsulated in POEPOP(1500)-resin is described. This polymer-supported catalyst has been successfully used in solution phase hydrogenation of a double and a triple bond as well as hydrogenolysis of a benzyl-protecting group. While the activity of the new catalyst is marginally lower than standard 10% Pd/C, it has the advantage of being reused several times without significant loss of reactivity.

The nitro group in aromatic nitro compounds also containing reducible substituents such as carbonyl, ethene, ethyne, nitrile, acid, phenol etc, is selectively and rapidly reduced at room temperature to corresponding amino derivatives in good yield employing formic acid in the presence of 10% palladium on carbon. The catalyst could be recovered and reused after washing with water and ethanol, and the results obtained indicate further, there is no apparent loss of catalytic activity.

[7440-05-3] Pd (MW 106.42) InChI = 1S/Pd InChIKey = KDLHZDBZIXYQEI-UHFFFAOYSA-N (catalyst for hydrogenation of alkenes, alkynes, ketones, nitriles, imines, azides, nitro groups, benzenoid and heterocyclic aromatics; used for hydrogenolysis of cyclopropanes, benzyl derivatives, epoxides, hydrazines, and halides; used to dehydrogenate aromatics and deformylate aldehydes) Solubility: insol all organic solvents and aqueous acidic media. Form Supplied in: black powder or pellets containing 0.5–30 wt % of Pd (typically 5 wt %); can be either dry or moist (50 wt % of H2O). Analysis of Reagent Purity: atomic absorption. Handling, Storage, and Precautions: can be stored safely in a closed container under air but away from solvents and potential poisons such as sulfur- and phosphorus-containing compounds. Pyrophoric in the presence of solvents. General precautions for handling hydrogenation catalysts should be followed. The catalyst must be suspended in the organic solvent under an atmosphere of N2. During filtration the filter cake must not be allowed to go dry. If a filter aid is necessary, a cellulose-based material should be used if catalyst recovery is desired.

(Pd) [7440-05-3] Pd (MW 106.42) InChI = 1S/Pd InChIKey = KDLHZDBZIXYQEI-UHFFFAOYSA-N (Et3N) [64-18-6] C6H15N (MW 101.22) InChI = 1S/C6H15N/c1-4-7(5-2)6-3/h4-6H2,1-3H3 InChIKey = ZMANZCXQSJIPKH-UHFFFAOYSA-N (HCO2H) [121-44-8] CH2O2 (MW 46.03) InChI = 1S/CH2O2/c2-1-3/h1H,(H,2,3) InChIKey = BDAGIHXWWSANSR-UHFFFAOYSA-N (transfer hydrogenation system used with a variety of palladium catalysts for hydrogenation and hydrogenolysis reactions; hydrogenation of alkynes, alkenes, nitro compounds; hydrogenolysis of N-benzyl and O-benzyl groups; hydrogenolysis of allyic esters and allylic carbonates) Alternate Name: triethylammonium formate (TEAF). Physical Data: see Palladium on Carbon, Triethylamine, and Formic Acid. Solubility: heterogeneous catalyst system.

We showed earlier that catalysts obtained by depositing nanodimensional palladium on various nanocarbon materials: fullerenes, nanotubes, fullerene soot, and also activated coconut carbon [1, 2] possessed substantially higher catalytic activity in alkene hydrogenation in comparison with industrial catalysts, where palladium was deposited on activated carbon. At the same time, we found that the nature of nanocarbon material has no essential effect upon catalytic activity. The obtained catalysts posses a pronounced affinity towards hydrogen absorption. The dependence of the absorbed hydrogen amount on the palladium content in the catalyst is of extremal character. The absorption maximum is achieved at comparatively low palladium content in the catalyst (0.1 wt %) and equals to 30– 35 mol of Н2 per 1 mol of Pd.

Electrocatalytic hydrogenation of benzaldehyde in acid hydroalcoholic solution has been studied at porous electrodes prepared by deposition of palladium on carbon felt. Preliminary results obtained by means of cyclic voltammetries, steady-state current-voltage curves and several series of preparative electrolyses are presented.

A simple two-step approach to methyltartronic acid (2-hydroxy-2-methylpropanedioic acid, 3) from methacrylic acid (1) via α-methylglyceric acid (2) is described. It is based on the successive use of hydrogen peroxide and oxygen as oxidants in the same aqueous medium, in combination with tungstic acid and palladium on carbon as catalysts, respectively

A novel and simple protocol for the reductive cross-coupling of halobenzenes (PhX; X = Cl, Br, I) with pyridine is presented, using catalytic (0.5 mol%) palladium on carbon. Catalyst regeneration is effected using molecular hydrogen generated in situ from the palladium-catalysed reduction of water with zinc powder. Notably, this transformation does not require the presence of reactive B(OH)2 or SnBu3 groups. Three separate processes are observed: cross-coupling (PhX + pyridine), homocoupling (PhX + PhX), and hydro-dehalogenation (reduction of PhX to PhH). The cross-coupling is regiospecific, forming only the 2-phenylpyridine isomer (ca. 50% isolated yield). The influence of various reaction parameters (temperature, reagent concentrations, and additives such as NaOH or a phase-transfer agent) on substrate conversion and product distribution is examined. Kinetic studies show the reaction rate is a function of zinc loading, catalyst loading, substrate concentration, and, above all, of the amount of water present. Possible mechanisms for the three processes in this system are discussed. It is proposed that the cross-coupling occurs via the formation of phenyl free-radicals, which subsequently react with pyridine molecules adsorbed on the catalyst surface.

A method has been developed for the synthesis of 2,2′- and 3,3′-biquinolines and of 4,4′-bipyridine based on the coupling of 2- and 3-bromoquinoline or 4-bromopyridine using a Pd/C-hydrazine-KOH catalytic system.

The synthesis of acyl glucuronides of common bile acids is described. By means of the Mitsunobu reaction employing diethylazodicarboxylate and triphenylphosphine, bile acids were condensed through the inherent C-24 carboxy group with benzyl 2,3,4-tri-O-benzyl- d -glucopyranuronate, which was prepared from 1-O-methyl-α- d -glucose. The separation and purification of the β-anomers at the anomeric position of the sugar moiety were attained by preparative thin-layer chromatography and/or high-performance liquid chromatography on a column packed with phenyl-bonded silica using H2O-MeOH as a mobile phase. The removal of the benzyl group on the sugar moiety was achieved by catalytic hydrogenation with 10% palladium on carbon to yield the desired acyl glucuronides of bile acids. The structures of these acyl glucuronides were confirmed by proton nuclear magnetic resonance spectral properties.

To investigate the anchoring of precious metals onto carbon fibrils Pd/C-fibril samples were investigated in both the precursor and the reduced state by X-ray absorption fine structure (XAFS) spectroscopy. Analysis of the XAFS data of the freshly prepared catalyst showed a palladium–tetraamine complex in interaction with carbon. The proposed model involves [Pd(NH3)4]2+ coordinated to the carbon fibril surface, most probably stabilised by the carboxylic groups (through O–H bridging and charge balance) and the π-electron system of the support. After insitu reduction, analysis pointed to small palladium particles of ca. 15 A present on the fibrils with a significant Pd–C interaction.

cis-1,2,3a,4,5,9b-Hexahydro-3H-benz[e]indoles were synthesized and evaluated for in vitro dopamine D1 and D2 receptor binding affinity. The target compounds 21-25 were readily prepared by reduction of the air-sensitive tricyclic enamines 10-14. Reduction of 10-14 with sodium borohydride, sodium cyanoborohydride, palladium on carbon in ethanol, and platinum oxide in ethanol or acetic acid gave only the cis (3a,9b) 1,2,3a,4,5,9b-hexahydro-3H-benz[e]indoles. The stereochemistry was confirmed by single-crystal X-ray analysis. In the 6-hydroxy series, the binding affinity at D1 and D2 receptors was of the order 22 (N-n-butyl) > 21 (N-n-propyl) > 23 (N-H). The compounds demonstrated greater binding affinity at D2 receptors than at D1 binding sites. In contrast, 8-OH derivatives exhibited affinity only for D2 receptors, with 25 (N-n-butyl) having slightly greater affinity than 24 (N-n-propyl).

A mild, efficient and LiCl-free synthetic method for indole derivatives based on the heteroannulation of alkynes with 2-iodoanilines was achieved using palladium on carbon (Pd/C) and NaOAc in heated NMP. The N-tosyl protection of 2-iodoaniline expedited the reaction progress, while other protecting groups, such as tert-butoxycarbonyl, acetyl, and benzyloxycarbonyl groups, underwent deprotection under the present conditions. A variety of di- and monosubstituted alkynes could effectively react with N-tosyl-2-iodoaniline to give the corresponding indoles in good to high yields.

A series of 3-alkyl-4-aminobutanoic acids were prepared via the Michael addition of nitromethane to 2-alkenoic esters, followed by catalytic hydrogenation of the resultant 3-(nitromethyl)alkanoic esters using 10% palladium on carbon in acetic acid, and acid hydrolysis of the reduction products

A mild and efficient protocol for the phosphine-free Suzuki-Miyaura coupling reaction of aryl bromides with arylboronic acids has been developed which utilizes the commercially available 10% Pd/C (3.5 mol% Pd) in ethanol-water (1:1) and Na 2 CO 3 at room temperature. The reaction is convenient, environmentally benign and generates excellent yields of the coupled products (94-100%). The catalyst can be recycled using simple filtration and washing sequences without significant decrease in the yield of coupling product up to the fourth run.

The palladium-catalyzed carbonylation reactions of pentachloropyridine and 2,3,4,5-tetrachloropyridine were investigated in alcoholic or aqueous solvent. The high boiling alcohol 2-ethyl-1-hexanol was an effective carbonylation solvent above 100 °C at 1 atm of CO, representing a convenient and simple method for carrying out transition metal catalyzed carbonylation reactions using standard laboratory glassware.

Sodium methoxide catalyzed aldol condensation of ethyl α-azidoacetate with 4-[bis-(tert-butoxy)phosphorylmethyl]benzaldehyde (4) provides methyl α-azido-4-[bis(tert-butoxy)phosphorymethyl]cinnamate (5), which undergoes facile hydrogenation in the presence of 10 % palladium on carbon to yield methyl 4-[bis(tert-butoxy)phosphorylmethyl]-DL-phenylalaninate (6)

Pd-Catalyzed Deuterium Exchange of Octa(silsesquioxane) H8Si8O12 to D8Si8O12 Deuterium exchange on octa(silsesquioxane) H8Si8O12 to D8Si18O12 catalyzed by palladium on carbon is reported.

The synthesis of pyrroloisoquinolinediones from phthalic anhydride and pyrrolylmagnesium halides has been improved. A new synthesis, by cyclization of the novel 1-(2-carboxybenzoyl)pyrroles, was generally preferable. From pyrrolylmagnesium bromide and dimethylmaleic anhydride, followed by cyclization, 6,7-dimethylindolizine-5,8-dione was obtained. The process failed with maleic anhydride. Pyrrolo[1,2-b]isoquinoline-5,10-dione could be dinitrated in the pyrrolo ring (with some oxidation to isoquinoline-1,3,4-trione), reduced to 10-hydroxy-3,5-dihydropyrrolo[1,2-b]isoquinolin-5-one by zinc and acetic acid, and hydrogenated over palladium on carbon to 10-hydroxy-1,2,3,5-tetrahydropyrrolo[l,2-b]isoquinolin-5-one. The dihydro derivative reverted in air to the dione.

A convenient synthesis of α-hydroxy-β-lactams has been devised that involves the annelation of an inline with benzyloxyacetyl chloride and triethylamine and subsequent hydrogenolysis in the presence of palladium on carbon. In most cases a cis-β-lactam was obtained. A thioimidate can also be used as the imino component in the annelation reaction but the hydrogenolysis step fails. The annelation of the appropriate thiazoline to a 6-epi-penicillin derivative occurred much more readily with benzyloxyacetyl chloride than with azidoacetyl chloride.

Resume Carborane aldehydes are prepared by the reaction of the corresponding carboxylic acid chlorides with triethylsilane catalyzed by 5 % palladium on carbon. The results are compared with the previously reported reaction of lithiocarboranes and diethylphenyl orthoformate

The synthesis of d, l, -12-bromocamptothecin (2d) from camptothecin (1) is described. Reduction of the bromo derivative 2d with tritium gas in the presence of palladium on carbon afforded d, l-camptothecin 12-3H having a specific activity of 29 Ci/mmol. A simpler labelling procedure was subsequently discovered whereby deuterium in the presence of palladium on carbon reduced ring B of camptothecin and also exchanged the C-5 hydrogen with deuterium. The reduced camptothecin aromatized to camptothecin in the presence of air to give deuterium incorporation in the C-5 and C-7 positions.

The 1-substituted-3-aryltetrahydroisoquinolines I have been converted into the corresponding 3,4-dihydroor isoquinoline derivatives by treatment with several oxidizing agents: iodine in ethanol, palladium on carbon, DDQ and Fremy's salt. The oxidation reactions with iodine always resulted in the formation of the 3,4-dihydroisoquinolines II, whereas the use of palladium on carbon and the DDQ led to the aromatic isoquinolines. Both the 3,4-dihydro- and the isoquinoline derivatives were obtained by means of Fremy's salt.

Vacuum deposition of ultrathin films of platinum and palladium on carbon and alumina supports at a substrate temperature of 350–400 °C and a working pressure of 10−5 Torr is shown to give rise not only to metallic particles but also to the formation of two new cubic oxides, namely, an NaCl-type (space group Fm3m, Z = 4) and a Cu2O-type oxide (space group Pn3m, Z = 2) with lattice parameters: PtO a = 0.515 ± 0.005 nm PdO a = 0.565 ± 0.005 nm Pt2O a = 0.395 ± 0.005 nm Pd2O a = 0.428 ± 0.005 nm Electron microscopic observations reveal that the NaCl-type oxide is in the form of thin, well-spread single crystals, whereas the fine dispersed particles correspond to metal and/or Cu2O-type oxides. It seems that the partial pressure of oxygen at 10−5 Torr is enough for finely divided platinum or palladium to form oxides at 350–450 °C. The existence of these new oxides in the bulk state has yet to be established, however. The formation of Pt2O and Pd2O suggests a valency of one for platinum and palladium in certain situations. Alternatively, these oxides may exhibit non-stoichiometry.

Die Pyrido[3,2-g]chinoline 1b, c und e werden erstmals unmittelbar durch Friedlander-Kondensation aus 4,6-Diaminoisophthalaldehyd (6) mit Ketonen dargestellt. Kupfer(I)-katalysierte Decarboxylierung der 2,8-Dicarbonsaure 1e fuhrt in Diethylenglycolmonomethylether bereits bei 165°C in guter Ausbeute zur Stammverbindung 1a. Trotz sterischer Hinderung durch eine tert-Butylgruppe addiert sich Methyllithium an die 2-Stellung der 2,8-Di-tert-butylverbindung 1c, wobei das 1,2-Dihydropyrido[3,2-g]chinolin 9 entsteht. Die Dehydrierung des Octahydrochino[3,2-b]acridins 7 mit Palladium auf Kohle bei 250°C ergibt 1,2,3,4,7,12-Hexahydro- (10) und 5,14-Dihydrochino[3,2-b]acridin (11). Synthesis and Reactions of Some Pyrido[3,2-g]quinolines (1,8-Diazaanthracenes) The pyrido[3,2-g]quinolines 1b, c, and e are synthesized for the first time directly by Friedlander condensation from 4,6-diaminoisophthalic aldehyde (6) and ketones. Copper(I)-catalyzed decarboxylation of the 2,8-dicarboxylic acid 1e occurs in diethylene glycol monoethyl ether at temperatures as low as 165°C affording the parent compound 1a in high yield. Despite steric hindrance by a tert-butyl group methyllithium adds to position 2 of the 2,8-di-tert-butyl compound 1c producing the 1,2-dihydropyrido[3,2-g]quinoline 9. Dehydrogenation of the octahydroquino[3,2-b]acridine 7 using palladium on carbon at 250°C yields the 1,2,3,4,7,12-hexahydro- (10) and the 5,14-dihydroquino[3,2-b]acridine (11).

Phenol and Cyclohexanol are simultaneously aminated to aniline and cyclohexylamine by ammonolysis with the palladium-on-carbon catalyst in the liquid phase, although the amination of either phenol or cyclohexanol hardly occurs without the other. In contrast, carbon-supported ruthenium, rhodium, and platinum catalysts are ineffective for this co-amination; they are active only for the amination of cyclohexanol to cyclohexylamine. These results are explained by the specific activity of palladium for hydrogen transfer between phenol and cyclohexanol.

We report the preparation and evaluation of palladium catalysts made from polyethylenimine (PEI)/silica composites. PEI was adsorbed to either porous silica beads or silica gel. Following crosslinking, the material was leached with base to increase the surface area and availability of the polymer. The PEI/silicas rapidly chelate Pd 2+ from solution. Reduction of the chelated metal ions can be accomplished with sodium borohydride. Pd/PEI/silica beads are used effectively in suspension with formic acid as the hydrogen donor; deprotection of Cbz-Glycine-O-t-butyl (where Cbz=carbobenzoxy) is very rapid with this catalyst compared to palladium on carbon. The Pd/ PEI/silica gel catalyst can be used effectively with hydrogen gas for the reduction of nitrobenzene in methanol. Both catalysts are conveniently separated from product by simply decanting the supernatant solution. The catalysts (1% Pd) have shown no pyrophoric behavior and they are reusable. Hydrophobic derivatives of the catalysts were prepared with the hope that apolar reactants would be attracted to the metal sites with a concomitant enhancement of rate. The introduction of apolar groups into the catalyst matrix did not, however, result in a more effective catalyst compared to the catalyst made from the unmodified material.

The bismethylenedioxy (BMD) derivative of dexamethasone 2 was silylated with trimethylchlorosilane and imidazole in dimethylformamide to give the 11β-trimethylsilyloxy BMD derivative 3. The Δ1 -double bond in 3 was hydrogenated over 5% palladium on carbon to give the Δ4-3-oxo steroid 4. Oxidation of 4 with potassium permanganate-sodium metaperiodate gave the seco-acid 5 which on subsequent treatment with acetic anhydride; sodium acetate and triethylamine gave the enol-lactone 6. The enol-lactone 6 was reacted with 14C-methylmagnesium iodide to give an adduct 7a which on heating at reflux with lithium 2,6-di-t-butylphenoxide in dioxane gave the Δ4-3-oxo derivative 8. Compound 8 was heated at reflux with m-iodylbenzoic acid and diphenyl diselenide in toluene to give the Δ1,4-3-oxo steroid 9. The protecting BMD and silyl groups were removed in a single step by reaction with aqueous trifluoroacetic acid containing 2N hydrochloric acid at room temperature to give dexamethasone-4-14C 10.

The three-dimensional structures of the products of catalytic hydrogenation of sym-octahydrothioxanthylium salts in the presence of palladium on carbon were studied by 13C NMR spectroscopy. It was shown that the reaction proceeds stereoselectively with the formation of cis-syn-cis isomers. The stereochemistry of the reduction products is in agreement with the previously proposed reaction mechanism.

The free hydroxyl groups in triamcinolone acetonide (1) were protected as silyl ethers to give the bis-silyloxy derivative 4. Compound 4 was then hydrogenated over 5% palladium on carbon to give the Δ4-3-oxo steroid 5 which was then converted to the enol-lactone 7 under selective reaction conditions. The enol-lactone 7 was subjected to Grignard reaction with 14C-methylmagnesium iodide to give an adduct 8a which on subsequent treatment with lithium 2,6-di-t-butylphenoxide gave 4-14C-Δ4-3-oxo derivative 9. Compound 9. was heated with selenium dioxide in t-butanol containing pyridine to give the Δ1,4-3-oxo derivative 10. Removal of the silyl protecting groups was readily accomplished by heating 10 with hydrochloric acid in methanol-tetrahydrofuran solution to give the title compound 11.

The analysis of the mechanism and characterization of low coverage deposits is accomplished by extrapolation of nucleus density and mean size data from higher coverage deposits, and from counts on zinc-amplified nuclei at low coverage. The results are consistent with a mechanism proposed earlier. Particles nucleate and grow principally by direct impingement on particularly active substrate sites. Failing to strike an existing nucleus or an active site, an incident atom becomes deactivated, possibly by diffusing into the substrate. Values of the active-site density and the active-site capture area are determined for each nucleus-substrate combination.

The reduction of aryl nitro groups by the palladium-sodium borohydride system can be controlled in some instances to give products differing from those of catalytic hydrogenation. With six equivalents of borohydride added to the catalyst 2,2′-dinitrobiphenyl formed only 2,2′-diaminobiphenyl. With added sodium hydroxide and varying amounts of borohydride and catalyst, the reduction can be controlled to give benzo[c]cinnoline, benzo[c]cinnoline 5-oxide or benzo[c]cinnoline 5,6-dioxide. In a closed system, the reagents reduce both the nitro and olefin functional groups in 6-nitro-5,8-dimethoxy-1,4-dihydro-1,4-ethano-naphthalene. In an open flask flushed with argon, the reduction is confirmed to the nitro group. Reduction of 2-chloro and 4-chloronitrobenzene with palladium-borohydride gives substantial yields of the appropriate chloroanilines. In contrast, hydrogen and palladium give aniline as the major product from each of these. These results suggest that the addition of sodium borohydride to palladium on carbon produces a reductive entity differing from that of catalytic hydrogenation.

Dibenzylmercury was completely decomposed within 20 min in refluxing xylene in the presence of a catalytic amount of 5% palladium on carbon, giving mercury and dibenzyl. The generation of benzyl radicals was confirmed by the formation of 1,3-adduct to α-phenyl-N-benzylnitrone and 9,10-adduct to anthracene. Other alkylmercurials showed a similar but less satisfactory result.

UDC 547.856.7.07:542.941.8 2,3-Dihydroperimidines are dehydrogenated smoothly by sodium pyrosulfite in refluxing aqueous alcohol, as a result of which the corresponding perimidines are formed in high yields. The reaction of 1,8-naphthalenediamine with the aldehydic forms of sugars gives 2-polyhydroxyalkyl-2,3-dihydroperimidines, which are also aromatized by sodium pyrosulfite to give the corresponding 2-polyhydroxyalkylperimidines in high yields. In 1965 Ridley and co-workers [2] found that the corresponding 2-substituted benzimidazoles and perimidines rather than the expected 2,3-dihydro derivatives are formed in high yields when o-phenylenediamine or 1.8-naphthalenediamine is heated briefly with the bisulfite adducts of aldehydes. It was assumed [2] that the intermediately formed benzimidazolines and 2,3-dihydroperimidines are oxidized during the reaction by the bisulfite ion to give the aromatized structures. Bisulfites are also of interest to biochemists [3], since they oxidize coenzyme NAD-H to NAD +. However, the dehydrogenating properties of the bisulfite ion have not yet been studied. We do not know of any studies in which bisulfites have been used for the preparative oxidation of genuine dihydro derivatives of heterocycles. With respect to the mechanism of the reaction, there are contradictory data on the conversion of bisulfite in the case of reduction by organic compounds to thiosulfate and dithionate ions [4] or dithionite ion [5]. It has also been assumed [3] that the reaction is a free-radical process that takes place with the participation of air oxygen and a superoxide anion radical, during which the bisulfite ion is actually a catalyst (an electron carrier). The aim of the present research was to study the dehydrogenating capacity of bisulfites in the 2,3-dihydroperimidine (I) series, since most of the methods for dehydrogenation of them (with sulfur [6], palladium on carbon [7, 8], and chloranil or manganese dioxide [9]) require relatively severe conditions and do not always proceed sufficiently smoothly. This makes it impossible to use them for the dehydrogenation of compounds that contain labile and easily oxidized substituents. In addition, the synthesis of only one perimidine derivative (2-phenylperimidine) [2] has been described, and the dehydrogenation of genuine 2,3-dehydroperimidines has not been studied at all. Instead of bisulfite we used sodium pyrosulfite (Na2S205, SPS), which is easier to use. The reaction was carried out by refluxing an aqueous alcohol solution of equimolar amounts of I and SPS. The results of experiments involving the dehydrogenation of various 2,3-dehydroperimidines with SPS are presented in Table I. Both 2,3-dihydroperimidine itself and its 2-substituted derivatives with alkyl, phenyl, or ~-surplus heteroaromatic (2-furyl, 2-thienyl, l-methyl-2-benzimidazolyl, etc.) groups as substituents undergo quantitative dehydrogenation in ~2 h under the indicated conditions.

In the asymmetric synthesis of chiral compounds the reduction of prochiral unsaturated reactants has a great importance. The use of proline as a chiral agent in hydrogenations, where the proline is applied as homogeneous chiral catalyst in ring-closure reactions of triketones, was reported previously. In this paper Proline is used in the hydrogenations of α-β unsaturated ketones or acetophenone with palladium on carbon catalysts, producing saturated ketones or α-phenyl-ethyl-alcohol of 5–60% optical purity. The influence of parameters on optical yield is also investigated. UV, NMR and circular dichroism measurements allow to propose the following mechanism: the zwitterionic form of proline gives a Schiff-base or enamin with the ketones; in the hydrogenation of this compound asymmetric induction takes place, which results in optically active ketones after hydrolizing the saturated product.

Solid sodium formate is an efficient hydrogen donor for Pd/C-catalyzed transfer hydrogenation of olefins, acetylenes and nitro compounds in the presence of an equimolar amount of water at exceedingly mild conditions. The reaction proceeds mainly by a direct hydrogen transfer mechanism rather than via initial decomposition of the formate into molecular hydrogen and carbon dioxide.