Hydrogenation procedure

Earlier, the reduction of y-nitro esters with zinc and ammonium chloride had been shownto provide a suitable route to A-hydroxy 2-pyiTolidones, e.g., 42. Various catalytic hydrogenation procedures can also effect the same reductive cyclization. ... 

Nielson125 reports the synthesis of 7-((V-aIkylamino)- and T-(N,N-di-alkylamino)-l,3,5-triazaadamantanes by reductive alkylation of 94, which is obtained from 91 by an improved hydrogenation procedure (rhodium-charcoal catalyst, 25.5 psi). Paper chromatography54 and the Kovats indices and relative elution volumes of 1,3,5-triazaadamantane derivatives are measured.55 7-Amino-l,3,5-triazaadamantane is used as a vulcanization accelerator.127 7-(N,N-Dialkylamino)-l,3,5-triazaadamantanes are utilized as a new class of high-density fuel (DIADAM).128 Some 7-substituted 1,3,5-triazaadamantanes have bacteriostatic and fungistatic activity.129 7-Bromo-,... 

This new hydrogenation procedure is clean, mild, and effective. It offers a very practical method for chiral alcohol synthesis. Isolated Ru complexes are fairly air and moisture stable and can be stored in an ordinary vial for quite a long time. Compared with the catalysts prepared in situ, the reaction rates in the asymmetric hydrogenations catalyzed by 70 are higher by two orders of magnitude. 

Stirring is provided by magnetic stirring bars, and heating by means of oil baths. Such apparatus can withstand pressures up to about 125 atm. The progress of the reaction is controlled by measuring the decrease in the pressure of hydrogen Procedure 3, p. 203). 

If R = benzyl, this substituent can be hydrogenoiysed after, or as a part of, the hydrogenation procedure [i.B- without the isolation of the intermediate N-alkylpiperidine). 

An efficient asymmetric hydrogenation of a-acetamidocin-namic acids has been achieved using a rhodium-chiral phosphine catalyst. This paper describes the preparation of the catalyst and the hydrogenation procedure as well as studies on structure vs. activity. 

Hydrogenation Procedure A. To a 60 ml pressure bottle equipped with a magnetic stirrer was added 20 ml of methanol and 1.00 gram of a-benzamido-4-hydroxycinnamic acid and 0.0038 gram bis [ (+) -o-ani-sylcyclohexylmethylphosphine] 1,5-cyclooctadiene rhodium tetrafluorobo-... 

Hydrogenation procedure. The steroid (0.2 mmoles) was dissolved in the donor alcohol (6 ml) and the solution heated to 90°C, transferred, under N2, in the reaction vessel where the catalyst (150 mg) had been previously pretreated and stirring was begun. 

The hydrogenation procedure consisted of adding the lignin to phenol in a ratio of 1 part lignin to 3 parts phenol. After adding the catalyst (10% based on lignin), the mixture was placed in the 2-liter Magne Dash... 

If, by means of catalyst improvements which are not obvious at the present time, the monophenol yield could be improved by, say 50%, the process should become profitable. Another area of improvement lies in reducing lignin preparation costs still further. This is for the future, however. At present, the Noguchi process is the best hydrogenation procedure which has yet been developed for converting lignin into chemicals. 

K. Tanaka and W. Pigman, Improvements in hydrogenation procedure for demonstration of O-threonine glycosidic linkages in bovine submaxillary mucin, J. Biol. Chem., 240 (1965) PC1487-PC1488. 

Elementary analyses indicated that the sugar moieties of pyrimidine nucleosides derived from deoxyribonucleic acid are also of the deoxypen-tosyl type. Early attempts to apply the hydrogenation procedure of Levene and LaForge60 were unsuccessful. It was generally assumed, however, that the sugar portion of the pyrimidine nucleosides of deoxyribonucleic acid is probably also of the 2-deoxy-D-ribosyl type. 

Attempts to prepare this hydrocarbon from benzanthrone by the Wolff-Kishner method (formation and hydrolysis of the hydrazone) or its modifications, by Raney nickel reduction, or by zinc-dust distillation were either unsuccessful or gave the desired hydrocarbon in poor yield. The successful reduction using synthesis gas demonstrates further the potentialities of this new hydrogenation procedure in problems of synthetic organic chemistry. 

Benzyl-1,3,6-dioxazocane 69 was smoothly deprotected under standard hydrogenation procedure (Scheme 14 <2001H(54)151 . 

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