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The total synthesis of (±)-royleanone (I) has been achieved. 5,7,8-Trimethoxy-1-tetralone (III) was converted into (±)-5,7,8-trimethoxy-1-methyl-2-tetralone (VII) via a dihydronaphthalene derivative (IV). The annelation of VII with methyl vinyl ketone gave a (±)-hexahydro-2-oxophenanthrene derivative (VIII), which was then further converted into (±)-11,12,14-trimethoxy-3-oxopodocarpa-5,8,11,13-tetraene (IX). The hydro-genation of IX over platinum oxide gave two dihydro derivatives, (X) and (XI), in a ratio of ca. 1 : 7, these configurations in the A/B ring juncture were identified as trans and cis respectively. Therefore, IX was subjected to thioketalization, followed by desulfurization, to give (±)-11,12,14-trimethoxypodocarpa-5,8,11,13-tetraene (XV). The hydrogenation of XV over 10% palladium on carbon gave (±)-11,12,14-trimethoxypodocarpa-8,11,13-triene (XII), along with a small amount of its cis isomer (XIII). Finally, XII was converted into a hydroxy-1,4-quinone derivative (XIX), which was then treat...

Aqueous sodium and potassium formate solutions undergo catalytic decomposition, under mild conditions, into molecular hydrogen and hydrogen carbonate in the presence of palladium on carbon. Both the formate and water hydrogen atoms are involved in the process and undergo fast exchange. Some kinetic and mechanistic features of the decomposition reaction are reported.

La deuteriation catalytique des acides maleique et fumarique et des esters correspondants par Pd/c est une methode importante et utile d'incorporation stereospecifique de deuterium vicinal

Reductive cyclizations of N-[2-(2-pyridyl)ethyl]imides were accomplished by employing a palladium on carbon catalyst in ethanolic acetic acid as the hydrogenation medium. Reduction of the corresponding N-[2-(2-quinolyl)ethyl]imides ceased at the 1,2,3,4-tetrahydroquinolyl stage. Controlled reduction of the tetrahydroquinolyl imides with sodium borohydride gave amido alcohols which afforded bridgehead nitrogen heterocycles upon cyclodehydration.

1. Catalysts comprising palladium on carbon or zeolites, with a low Pd content (0.25–1%), are active and selective in respect of the carbonylation of ethylene, propylene, and 1-hexene to form carboxylic acids. 2. Catalysts comprising palladium on carbon are suitable for repeated use.

Syntheses of 1-methyl-2-phenyl-1, 2, 3, 4, 5-pentahydro-10H-benzo[5, 6]cyclohepta[1, 2-c]pyrazole-3, 10-dione (3a) and its aminoalkylidene derivatives (3b-d) were investigated. Treatment of 3a with N-bromosuccinimide gave 4 (5)-bromo-1-methyl-2-phenyl-1, 2, 3-trihydro-10H-benzo[5, 6]cyclohepta[1, 2-c]pyrazole-3, 10-dione (13), while reaction of 3a with N-chlorosuccinimide produced 2-phenyl-2, 3, 3a, 4, 5-pentahydro-10H-benzo[5, 6]cyclohepta[1, 2-c]pyrazole-3, 10-dione (15). Dehydrogenation of 3a at 310°with palladium on carbon catalyst afforded 1-methyl-2-phenyl-1, 2, 3-trihydro-10H-benzo[5, 6]cyclohepta[1, 2-c]pyrazole-3, 10-dione (18) in a trace.

The gas-phase acetoxylation of ethylene has been studied on a palladium-on-carbon catalyst, using a fixed-bed flow reactor in the temperature range 415 to 455 K. The extent of deviation in the lattice constant of palladium from expected values correlated with the decrease in the activity of a catalyst.

Ammonium formate catalytic transfer hydrogenolysis, in the presence of palladium on carbon, has shown utility for the rapid dehalogenation of mono-or polychlorinated aromatic compounds in neutral media under ambient conditions of temperature and pressure.

We report a simple method for synthesis of 4-hydroxy 6-methyl 3-β-arylpropionyl 2-pyrones 1 from 3-cinnamoyl 4-hydroxy 6-methyl 2-pyrones by selective hydrogenation at ambient temperature under pressure using 10% palladium on carbon as catalyst.

A much improved synthesis of the heretofore difficultly obtainable 2,6-diaminopyrazine (4) was afforded by the low-pressure catalytic hydrogenation (palladium on carbon) of 2,6-diazido-pyrazine (2); reaction of 2,6-dichloropyrazine (1) and sodium azide gave 2 in 84% yield. The outcome of the reduction was found to be solvent dependent: 1,2-dimethoxyethane containing aqueous ammonia gave 4 in 83% yield; 1,2-dimethoxyethane alone gave 5-aminotetrazolo[1,5-a]-pyrazine (3) in 26% yield. Additional alternative syntheses of 3 and 4 are described. A number of acyl and azo derivatives of 4 were prepared. Reactions of 2 with dimethyl acetylenedicarboxylate and ethyl acetate (base catalyzed) leading to vic-triazole derivatives are also described.

Allyl ethers are widely used for the “temporary” protection of hydroxy groups in carbohydrates. The allyl group is conveniently removed by isomerization and subsequent cleavage of the labile prop-1-enyl group.2 The rearrangement of allyl ethers to prop-1-enyl ethers is readily achieved by treatment with potassium t-butoxide in dimethyl sulfoxide, using tris(tripheny1phosphine)rhodium chloride, palladium on activated charcoal and by an ene reaction with diethylazodicarboxylate. acidic conditions, ozonolysis followed by alkaline hydrolysis, reaction with alkaline permanganate solution, or treatment with mercuric chloride in the presence of mercuric oxide. The isomerization of allyl ethers to prop-1-enyl ethers can also be carried out in the presence of palladium on carbon or complex bis(benzonitrile)palladium(11) chloride. Bruce and Roshan-Ali' showed that derivatives of allyl phenyl ether are smoothly cleaved by this complex. This has made it possible to remove the protecting group in a one-pot op...

17β-Hydroxy-[1ξ,2ξ-3H2]4,6-androstadien-3-one was prepared by the selective reduction of 17β-hydroxy-1,4,6-androstatrien-3-one in benzene with tritium over 5% palladium on carbon. After purification by thin layer chromatography and high pressure liquid chromatography, the specific activity was at least 37 Ci/mmol, and the radiochemical purity was greater than 96%.

Die alkylsubstituierten 2-(Trimethylsiloxy)cyclopropancarbonsaureester 8a – 8f werden von Wasserstoff in Gegenwart von Palladium auf Kohlenstoff durch Desilylierung zu den γ-Oxocarbonsaureestern 10a – 10e geoffnet. Dagegen ergeben die 2-phenylsubstituierten Cyclopropane 8g – 8j unter diesen Bedingungen die 4-Phenylbutansaureester 13g – 13j. Die Bildung von 13j erfolgt stereounselektiv. Der primaren Cyclopropanspaltung schliest sich hier eine Hydrogenolyse der benzylischen C – O-Bindung an. Diese Folgereaktion kann bei 8g durch Vergiftung des Katalysators mit Triethylamin, in anderen Fallen durch Einsatz der tert-Butyldimethylsiloxy-Verbindungen 11g – 11i verhindert werden. Die Butansaureester 14h bzw. 14i fallen als Diastereomerengemische an, was wiederum als Beleg fur stereounselektive Cyclopropanhydrogenolyse gewertet wird. Wahrend das 3-phenylsubstituierte Cyclopropanderivat 8k lediglich unter langsamer Desilylierung mit katalytisch erregtem Wasserstoff reagiert, findet man bei dem Vinylcyclopropan 8m auch teilweise eine Spaltung der 1 – 3-Bindung des Dreiringes. Regio- und Stereo-selektivitat der Hydrogenolyse der Donor-Acceptor-substituierten Cyclopropane 8 und 11 werden diskutiert. Alkyl-substituted methyl 2-(trimethylsiloxy)cyclopropanecarboxylates 8a – 8f are opened by hydrogen in the presence of palladium on carbon affording 4-oxoalkanoci esters 10a – 10e by desilylation. 2-Phenyl-substituted cyclopropanes 8g – 8j, however, provide 4-phenylbutanoic esters 13g – 13j under these conditions. Formation of 13j is not stereoselective. Here the primary cyclopropane cleavage is followed by hydrogenolysis of the benzylic C – O bond. This subsequent reaction can be suppressed in the case of 8g by poisioning the catalyst with triethylamine; otherwise the tert-butyldimethylsiloxy compounds 11g – 11i have to be used. Butanoic esters 14h and 14i, respectively, are formed as mixtures of diastereomeres, which is another indication for nonstereoselective hydrogenolysis of cyclopropanes. Whereas slow desilylation by hydrogen was observed with the 3-phenyl-substitued cyclopropane derivative 8k, the vinylcyclopropane 8m in part suffers cleavage of the 1 – 3 bond of the three-membered ring. Regio- and stereoselectivity of the hydrogenolysis of the donor-acceptor-substituted cyclopropanes 8 and 11 are discussed.

Asymmetric hydrogenations of N-(N-acetyldehydrophenylalanyl)-β-amino alcohol benzyl ethers were carried out by using either rhodium complexes with chiral and achiral phosphines or 10% palladium on carbon. The effects of the chiral center in the β-amino alcohol moiety on simple as well as double asymmetric induction are described.

1. The unsaturated bicyclic ketone (VIII) was obtained in 7% yield from the reaction of 2-bromomagnesium-6-methoxynaphthalene (I) with the methyl ether of dihydroresorcinol, and on being demethylated gave the model analog of homoequilenine (VII). 2. The reaction of p-anisylmagnesium bromide (X) with the methyl ether of dihydroresorcinol (II) led to the formation of 2-(p-methoxyphenyl)-Δ1-cyclohexen-6-one (XII) in 40% yield. 3. 6-(p-Hydroxy-o-methylphenyl)-1-tetrahydronaphthalone (XIX) was prepared by demethylation of 6-(p-methoxy-o-methylphenyl)-1-tetrahydronaphthalone (XX) with aluminum chloride in boiling xylene. 4. 6-(p-Hydroxyphenyl)-1-tetrahydronaphthalone (XXI) was converted into 6-(p-acetoxyphenyl)-1-tetrahydronaphthalone (XXIII) by boiling with acetic anhydride. 5. The tricyclic ketones (XXVII) and (XVIII) were isolated respectively by the action of the potassium derivative of 5-methoxy-2-tetrahydronaphmalone (XXVI) on 2-phenyl-1-bromoethane (XXIV) and 2-(m-methoxyphenyl)-1-bromoethane (XXV), and these after the cyclization with polyphosphoric acid and the subsequent dehydrogenation with palladium on carbon gave 1-methoxychrysene (XXXI) and 1,8-dimethoxychrysene (XXXII).

Autoxidation of methyl oleate and oleic acid beyond the peak peroxide values followed by catalytic hydrogenation gave mixed monohydroxystearic acids in high yield. The complicated autoxidation mixture which contains peroxides, hydroxy, carbonyl, and oxirane compounds was simplified considerably in composition by this procedure. For complete reduction of the double bond, and the carbonyl and oxirane groups, hydrogenation was conducted at about 150° and 150 lbs.. Peroxides were reduced at room temperature. Catalysts used were palladium on carbon and Raney nickel. The selective reduction of peroxides in autoxidation mixtures has been studied by chemical and catalytic means. Peroxides were converted largely to carbonyl compounds rather than to the anticipated hydroxy compounds. Palladium-lead on calcium carbonate is an excellent catalyst for reducing peroxides with hydrogen. tert-Butyl hydroperoxide, 12- ketostearic acid, stearone,cis-9,10-epoxystearic acid and methyl oleate peroxide concentrate were employed as model substances in determining hydrogenation conditions.

Hydrogenation of 7-methylenebicyclo[3.3.1]nonan-3-one (1) over platinum oxide in acetic acid yielded 7α-methylbicyclo[3.3.1]nonan-3α-ol (2) as the sole product. Hydrogenation of (1) in ethyl acetate afforded 7α-methylbicyclo[3.3.1]nonan-3-one (3) as a reduced product and 7-methylbicyclo[3.3.1]non-6-en-3-one (4) as an isomerized product. Hydrogenation of 1 over palladium on carbon gave no reduced product but 4 in 100% conversion. Hydrogenation of 7-methylenebicyclo[3.3.1]nonan-3α-ol (7) and -3β-ol (8) over platinum oxide in acetic acid gave 2 and 7α-methylbicyclo[3.3.1]nonan-3β-ol (5), respectively. From studies based on NMR spectroscopy with use of a shift-reagent, it is concluded that the major conformer of 2 and 5 is of chair-boat form. By the equilibration experiment between 2 and 5 using aluminum isopropoxide in isopropyl alcohol at 110°C, the ΔG° value was found to be −2.2 kcal/mol.

Aus dem leicht zuganglichen Tetrahydropyranylather 1 des 21.21-Dimethoxy-pregnenolons wird durch Wittig-Reaktion nebst Hydrolyse 2, daraus durch Michael-Addition 3 und nach dessen Verseifung sowie Decarboxylierung 5 erhalten. Ringschlus des 5-acetats fuhrt zu 7, aus dem durch Dehydrierung (Pd/Kohle) das α-Pyron 8 entsteht. – In Ubertragung dieser Reaktionsfolge auf 3-Athoxy-21.21-dimethoxy-20-oxo-pregnatrien (9) wird zwar in guten Ausbeuten das Enollacton 11 erhalten; nach dessen Dehydrierung gelang es aber nicht, das dunnschichtchromatographisch nachgewiesene 12 kristallin zu isolieren. Selektive Hydrierung von 11 fuhrt glatt zur 5β-H-Verbindung 14, deren Dehydrierung mit Pd/Kohle 16 ebenfalls nur in geringer Ausbeute ergibt. Bei Versuchen, die Ketogruppe von 11 zur 3β-Hydroxy-Gruppe (nach Meerwein-Ponndorf oder nach Henbest) zu reduzieren, um danach in die Bufalin-Reihe zu gelangen, findet bevorzugt die Hydrierung des Enollacton-Rings unter Bildung von 15 statt. Preparations of Unsaturated Lactones of the Steroid Group, VI. Synthesis of Bufadienolides. I Starting from the readily accessible tetrahydropyranyl ether 1 of 21,21-dimethoxypregnenolone, 2 is obtained by Wittig reacton and subsequent hydrolysis. By Michael addition of 2 to 3, followed by saponification and decarboxylation, 5 is synthesized, whose acetate undergoes ring closure to 7. Dehydrogenation of 7 by means of Pd on carbon leads to the α-pyrone 8. – Using this reaction sequence for the synthesis of a bufaline compound from the pregnatriene derivative 9, the enol-lactone 11 is obtainable in good yields. After dehydrogenation of 11 it is not possible to isolate 12, detected by thin layer chromatography, in a crystalline form. By selective hydrogenation of 11 the 5β-H-compound 14 is obtained. Its dehydrogenation with palladium on carbon results only in a low yield of 16. Other dehydrogenation methods for reduction of the keto group of 11 to the 3β-hydroxy group (according to Meerwein-Ponndorf of Henbest) have been tried; however, hydrogenation of the enol-lactone ring to 15 preferably occurs.

An alkylation of 3-amino-4-ethoxycarbonylpyrazole (1) under various conditions was investigated. Alkylated pyrazoles (2, 3a, b) were condensed with isocyanates or isothiocyanate to yield pyrazolylurea derivatives (4a-f, 10). Ring closure of these intermediates was carried out in a solution of sodium ethoxide and the resulting 2, 5 (or 1, 5)-disubstituted pyrazolo [3, 4-d] pyrimidines (5a-f, 11a, b) were alkylated to give 2, 5, 7 (or 1, 5, 7)-trisubstituted pyrazolo [3, 4-d] pyrimidines (6a-e, 12a, b) or 2, 5-disubstituted 6-methylmercaptopyrazolo [3, 4-d] pyrimidines (7a, b). Instead of the use of isocyanates, another methods by fusing ureas with methylpyrazole were also investigated. Furthermore, debenzylation of 2-benzylpyrazolo [3, 4-d] pyrimidines (6c, d) was carried out with 35 atm of hydrogen in an autoclave at 220°over palladium on carbon to give debenzylated compounds (13a, b).

1. The sequence of hydrogenation of carvone on platinum and palladium catalysts was investigated. 2. The hydrogenation of carvone on Pd-black proceeds nonselectively with the formation of carvotanacetone and carvomenthone. As a result of parallel reactions of isomerization and irreversible catalysis, carvacrol is formed. Palladium on carbon catalyzes the process differently from Pd-black. 3. Hydrogenation of carvone on Pt-black proceeds selectively through the successive formation of carvotanacetone, isomeric carvomenthones, and isomeric carvomenthols.

Satisfactory margarine stocks have been made with a palladium on carbon catalyst in laboratory, pilot plant, and plant processing. The catalyst was shown to make a satisfactory product even when, on continued re-use, the ratio of oil to metal used reached 400,000 to 1.

The kinetics of the hydrogenation of a series of alkyl- and dialkylnaphthalenes over palladium on carbon in acetic acid have been studied at 80 °C and atmospheric pressure. Selective formation of tetrahydro derivatives was always observed. Equilibration experiments of pairs of alkyltetralins showed that the hydrogenations are kinetically controlled. The mechanism of hydrogen addition is discussed, especially on the basis of deuteration experiments. Competitive hydrogenations showed that bulky alkyl substituents weaken the strength of adsorption. The rate of hydrogenation of 2-alkyl- and 2,6-dialkylnaphthalenes, except 2,6-di-t-butylnaphthalene, is somewhat lower than that of naphthalene. In 2-alkylnaphthalenes the unsubstituted ring is hydrogenated preferentially. For the 1-alkyl-naphthalenes and the 1,4-, 1,5-, and 1,8-dialkylnaphthalenes the rate of hydrogenation was found to increase sharply with growing size of the alkyl groups. In the case of 1-t-butyl- and 1,4-di-t-butylnaphthalene a highly selective hydrogenation of the substituted ring was observed. These phenomena are discussed in terms of peri strain, the steric interaction of the 1-alkyl group with the 8-hydrogen atom or 8-alkyl group. Partial release of this strain during hydrogenation is supposed to give rise to increased rates and to govern the selectivity of ring attack.

A kinetic study of substituent effects in the liquid-phase hydrogenation of the olefinic bond has been made using palladium on carbon as the catalyst. Individual and competitive hydrogenations have been carried out with 2-aryl-3-methyl-2-butenes (1) and substituted 3,4-dihydro-1,2-dimethylnaphthalenes (2) in basic, neutral, and acid media. Electronic substituent effects on the rate of hydrogenation are found to be rather small. The adsorbed state in the basic medium is not seriously influenced by the substituents. More substantial substituent effects on the strength of adsorption are observed in neutral and acid media. Coadsorption of the dimethylamino and ethoxycarbonyl group on palladium takes place. It is concluded that the electronic nature of the transition state of hydrogenation on palladium is quite similar to that of the initial state. Higher π-electron density at the olefinic bond favors the strength of adsorption; this is consistent with a π-bonded adsorbed olefin.

The synthesis of sulfones of thiacyclohexanes, thiadecalins, and perhydrothioxanthenes by the catalytic hydrogenation of the corresponding α,β-unsaturated cyclic sulfones in the presence of palladium on carbon was developed. The effects of the temperature conditions, excess hydrogen pressure, the nature of the grouping in the 4 position of the heteroring, and the degree of shielding of the double bond on the process were established.

The 1,4-cycloaddition of sulfene to N,N-disubstituted 5-aminomethylene-1,5,6,7-tetrahydro-2-methyl-1-phenylindol-4-ones afforded N,N-disubstituted 3,4,5,6-tetrahydro-8-methyl-7-phenyl-7H-1,2-oxathiino[6,5-e]indol-4-amine 2,2-dioxides only in the case of aliphatic N-substitution. The 1,4-cycloaddition of dichloroketene occurred normally only in the case of 1,5,6,7-tetrahydro-2-methyl-1-phenyl-5-piperidinomethyleneindol-4-one to give 3,3-dichloro-3,4,5,6-tetrahydro-8-methyl-7-phenyl-4-piperidino-7H-pyrano[2,3-e]indol-4-one. Attempted recrystallisation, dehydro-chlorination or treatment with palladium on carbon of this adduct, as well as reaction of similar enaminoketones with dichloroketene, gave instead the same product, namely 3-chloro-8-methyl-7-phenyl-7H-pyrano[2,3-e]indol-4-one, as a result of dehydrochlorination, dehydrogenation and subsequent hydrogenolysis of the C-NR2 bond in the primary adduct.

2-Pyrrolidylacetic acid and β-(2-pyrrolidyl)propionic acid hydrochloride have been prepared by hydrogenation of ethyl 2-pyrrolylacetate and diethyl 2-pyrrolylmethylenemalonate respectively, over rhodium on alumina in HCl solution, followed by acidic hydrolysis. Similarly, 1-methylnipecotic acid, 1-methylisonipecotic acid, 2- and 3-piperidine-acetic acid, and 3-piperidine-propionic acid hydrochlorides have been prepared by hydrogenation of the corresponding pyridine-alkanoic acid hydrochlorides over platinum oxide, rhodium on alumina, or palladium on carbon in water.

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

Treatment of compounds containing functional groups, such as alcohols, amines, and carboxylic acids, with t-butyldimethylsilane in the presence of a catalytic amount of palladium on carbon is described to provide a new, convenient method for the introduction of a t-butyldimethylsilyl (TBDMS) group.

By boiling naphthylene-1,8-diamine with 5-halogeno- and 5-nitrofurfural in benzene or xylene, 90–95% yields of the corresponding 2-(5-halogeno-2-furyl)- and 2-(5-nitro-2-furyl)-2, 3-dihydroperimidines have been obtained. The dehydrogenation of 2-(5-bromo-2-furyl)-2, 3-dihydroperimidine with palladium on carbon has given 2-(5-bromo-2-furyl)perimidine. The compounds obtained have been characterized by their UV and IR spectra.

Shortening stocks obtained in the pilot plant differ slightly from those obtained in the laboratory under nominally the same conditions. Pilot-plant processing is easily controlled to give a commercially attractive shortening at a cost competitive with nickel. By repeated re-use 1 g. of 5% palladium on earbon catalyst will hydrogenate about 18 kg. of oil to a satisfactory product, and 1 g. of 2% palladium on carbon catalyst about 11 kg. of oil.

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.

The synthesis of 2-aminomethyl-1,10-phenanthroline (4) from 1,10-phenanthroline (1) is described. The reduction of 2-cyano-1,10-phenanthroline (3) to 4 in the presence of 10% palladium on carbon in acetic acid under mild reaction conditions also proved to be a very efficient method for conversion of cyanopyridines to methylaminopyridines.

The 2′-deoxyribofuranose analog of the naturally occurring antibiotics SF-2140 and neosidomycin were prepared by the direct glycosylation of the sodium salts of the appropriate indole derivatives, with 1-chloro-2- deoxy-3,5-di-O-p-toluoyl-α-D-erythropentofuranose (5). Thus, treatment of the sodium salt of 4-methoxy-1H- indol-3-ylacetonitrile (4a) with 5 provided the blocked nucleoside, 4-methoxy-1-(2-deoxy-3,5-di-O-p-toluoyl-β- D-erythropentofuranosyl)-1H-indol-3-ylacetonitrile (6a), which was treated with sodium methoxide to yield the SF-2140 analog, 4-methoxy-1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indol-3- ylacetonitrile (7a). The neosidomycin analog (8) was prepared by treatment of the sodium salt of 1H-indol-3-ylacetonitrile (4b) with 5 to obtain the blocked intermediate 1-(2-deoxy-3,5-di-O-p-toluoyl-β-D-erythropentofuranosyl) −1H-indol-3-ylace-tonitrile (6b) followed by sodium methoxide treatment to give 1-(2-deoxy-β-D-erythropentofuranosyl)-1H- indol-3-ylacetonitrile (7b) and finally conversion of the nitrile function of 7b to provide 1-(2-deoxy-β-D- erythropentofuranosyl)-1H-indol-3-ylacetamide (8). In a similar manner, indole (9a) and several other substituted indoles including 1H-indole-4-carbonitrile (9b), 4-nitro-1H-indole (9c), 4-chloro-1H-indole-2-carboxamide (9d) and 4-chloro-1H-indole-2-carbonitrile (9e) were each glycosylated and deprotected to provide 1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indole (11a), 1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indole-4- carbonitrile (11b), 4-nitro-1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indole (11c), 4-chloro-1-(2-deoxy-β-D- erythropentofuranosyl)-1H-indole-2-carboxamide (11d) and 4-chloro-1-(2-deoxy-β-D-erythropentofuranosyl)- 1H-indole-2-carbonitrile (11e), respectively. The 2′-deoxyadenosine analog in the indole ring system was prepared for the first time by reduction of the nitro group of 11c using palladium on carbon thus providing 4-amino-1-(2-deoxy-β-D-erythropentofuranosyl)- 1H-indole (16, 1,3,7-trideaza-2′-deoxyadenosine).

Although the palladium-carbon interaction is important in catalysis no authentic palladium carbides appear to have been experimentally characterised. However, some unsubstantiated syntheses have been described and a number of theoretical studies have been reported. The use of palladium on carbon as a catalyst for the reduction of organic compounds is well documented in the literature of organic chemistry. A review is given in “Platinum” Suppl. Vol. Al 1985, pp. 225/7.

Two lignins obtained from aqueous methanol organosolv pulping of aspen wood have been liquefied when suspended in water and heated to slightly above the critical temperature of water. Liquefaction was carried out in a stirred autoclave in the presence of a palladium on carbon catalyst and a low partial pressure of hydrogen (730 psi). Injection of the aqueous lignin suspensions into a pre-heated autoclave permitted study of reaction time effects minimizing the effect of heat-up time. The lignins were converted in good yield to brown viscous oils, that were soluble in ethyl acetate. Other products included an ethyl acetate insoluble fraction (~10%) and carbon-containing gases (~10%), e.g. carbon monoxide, carbon dioxide, methane, ethane, etc. The highest yields (~70%) of oil were obtained after 5–20 minutes. Yields of oil decreased after 45 minutes with increasing formation of gases. The apparent molecular-weight distributions of the liquefied lignins were 2–3 fold smaller than the starting lignins, indicating substantial depolymerization had taken place. The volatile fraction of the oils contained syringols, guaiacols, catechols and phenol. Increasing reaction time converted syringols and guaiacols into catechols.

The synthesis of 2-aminomethyl-1,10-phenanthroline (4) from 1,10-phenanthroline (1) is described. The reduction of 2-cyano-1,10-phenanthroline (3) to 4 in the presence of 10% palladium on carbon in acetic acid under mild reaction conditions also proved to be a very efficient method for conversion of cyanopyridines to methylaminopyridines.

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.

The synthesis of sulfones of thiacyclohexanes, thiadecalins, and perhydrothioxanthenes by the catalytic hydrogenation of the corresponding α,β-unsaturated cyclic sulfones in the presence of palladium on carbon was developed. The effects of the temperature conditions, excess hydrogen pressure, the nature of the grouping in the 4 position of the heteroring, and the degree of shielding of the double bond on the process were established.

2-Pyrrolidylacetic acid and β-(2-pyrrolidyl)propionic acid hydrochloride have been prepared by hydrogenation of ethyl 2-pyrrolylacetate and diethyl 2-pyrrolylmethylenemalonate respectively, over rhodium on alumina in HCl solution, followed by acidic hydrolysis. Similarly, 1-methylnipecotic acid, 1-methylisonipecotic acid, 2- and 3-piperidine-acetic acid, and 3-piperidine-propionic acid hydrochlorides have been prepared by hydrogenation of the corresponding pyridine-alkanoic acid hydrochlorides over platinum oxide, rhodium on alumina, or palladium on carbon in water.

The total synthesis of (±)-royleanone (I) has been achieved. 5,7,8-Trimethoxy-1-tetralone (III) was converted into (±)-5,7,8-trimethoxy-1-methyl-2-tetralone (VII) via a dihydronaphthalene derivative (IV). The annelation of VII with methyl vinyl ketone gave a (±)-hexahydro-2-oxophenanthrene derivative (VIII), which was then further converted into (±)-11,12,14-trimethoxy-3-oxopodocarpa-5,8,11,13-tetraene (IX). The hydro-genation of IX over platinum oxide gave two dihydro derivatives, (X) and (XI), in a ratio of ca. 1 : 7, these configurations in the A/B ring juncture were identified as trans and cis respectively. Therefore, IX was subjected to thioketalization, followed by desulfurization, to give (±)-11,12,14-trimethoxypodocarpa-5,8,11,13-tetraene (XV). The hydrogenation of XV over 10% palladium on carbon gave (±)-11,12,14-trimethoxypodocarpa-8,11,13-triene (XII), along with a small amount of its cis isomer (XIII). Finally, XII was converted into a hydroxy-1,4-quinone derivative (XIX), which was then treat...

Aliphatic as well as aromatic acid chlorides are reduced smoothly into aldehydes at room temperature and atmospheric pressure by hydrogenation, using palladium on carbon as the catalyst, acetone or ethyl acetate as solvent and ethyldiisopropylamine as hydrogen chloride acceptor. The reaction has a high selectivity and under the conditions used, no over-reduction nor reduction of aromatic rings, of nitro and chloro substituents in benzoyl chlorides, or double bonds in cinnamoyl chlorides, was observed. The selectivity is probably the result of a combination of factors, such as selective adsorption of the acid chloride on the catalyst (with respect to the aldehyde) and partial poisoning of the catalyst surface by co-adsorption of ethyldiisopropylamine and its hydrochloride.

Treatment of 3-unsubstituted indolizines with a dehydrogenating agent such as palladium on carbon in refluxing xylene gave the corresponding 3,3′-biindolizine derivatives in 19–74% yields.

The 1,3-diones (I) and (V) are hydrogenated in the presence of palladium on carbon and catalytic amounts of sulfuric acid to form the monoketones (II) or (VI) and (VII).

Allyl ethers are widely used for the “temporary” protection of hydroxy groups in carbohydrates. The allyl group is conveniently removed by isomerization and subsequent cleavage of the labile prop-1-enyl group.2 The rearrangement of allyl ethers to prop-1-enyl ethers is readily achieved by treatment with potassium t-butoxide in dimethyl sulfoxide, using tris(tripheny1phosphine)rhodium chloride, palladium on activated charcoal and by an ene reaction with diethylazodicarboxylate. acidic conditions, ozonolysis followed by alkaline hydrolysis, reaction with alkaline permanganate solution, or treatment with mercuric chloride in the presence of mercuric oxide. The isomerization of allyl ethers to prop-1-enyl ethers can also be carried out in the presence of palladium on carbon or complex bis(benzonitrile)palladium(11) chloride. Bruce and Roshan-Ali' showed that derivatives of allyl phenyl ether are smoothly cleaved by this complex. This has made it possible to remove the protecting group in a one-pot op...

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.