New hydrogenation catalyst: palladium-poly(ethylenimine) "ghosts". Applications in peptide synthesis

Abstract

The weight losses which occurred as a result of these reactions suggested that the products of these reactions were water soluble. Similar treatment of isobutyronitrile and pivalonitrile gave principally water soluble products, and IR and GLC analyses of the small amounts of organic products from these nitriles showed the absence of starting materials.Conversion of Phenylacetonitrile to Benzonitrile. To a solution of 1.76 g (15 mmol) of phenylacetonitrile in 30 mL of CC14 was added 2.7 g of N-bromosuccinimide (NBS) and 25 mg of benzoyl peroxide. This solution was heated at reflux in the presence of a sunlamp for 30 min, the succinimide was removed, and the solution was concentrated to a yellow oil. This oil was added dropwise over a period of ca. 5 min to a solution of 3 g of sodium azide in 50 mL of Me2SO at room temperature. The solution was stirred for 15 min, poured into 1% NaOH solution, and extracted with pentane. The organic layer was dried, concentrated, and distilled to give 1.28 g (80%) of benzonitrile which was identified by comparison with an authentic sample.Acknowledgment. P. E. Nicholas thanks the Gillette Corp. for a fellowship.

Catalytic Transfer Hydrogenation of Bifunctional Poly(ethylene glycol) Derivatives Using Palladium−Poly(ethylenimine) Catalyst

“…To prevent breakdown of the Boc-PEG-NH 2 and Boc-PEG-Boc, the mixture once evaporated and crystallized, was diluted with water, partially evaporated at reduced pressure and then extracted into ethyl acetate. 5 After evaporation of the solvent a white solid material was obtained. A similar experiment was performed with the same mixture on palladium black as a catalyst, to compare the efficiency of the two systems.…”

“…The eluent was evaporated under reduced pressure. To prevent breakdown of the Boc-PEG-NH 2 and Boc-PEG-Boc, the mixture once evaporated and crystallized, was diluted with water, partially evaporated at reduced pressure and then extracted into ethyl acetate . After evaporation of the solvent a white solid material was obtained.…”

“…In this report, palladium−poly(ethylenimine) has been tested as an alternative catalyst. Poly(ethylenimine) has good mechanical and chemical stability and has been used as a support for metals. − Palladium−poly(ethylenimine) exhibits high catalytic activity and stability in the hydrogenolysis of the carbobenzoxy group (Z) and has been shown to be useful in the removal of this protective group from molecules such as small peptides and amino acids . This catalyst can be easily regenerated for further use with no loss of catalytic activity.…”

One-Pot Combination of Metal- and Bio-Catalysis in Water for the Synthesis of Chiral Molecules

“…Firstly, the authors assayed, as a model reaction, the hydrogenation of the watersoluble alkene caffeic acid catalyzed by the Royer palladium catalyst [60,61] in a reaction media able to allow the growth of Escherichia coli DD-2 (optical density (OD) = 0.4), which is responsible for the production of hydrogen from glucose employing an inducible pathway involving ferredoxin, a pyruvate ferredoxin oxidoreductase and a [Fe-Fe] hydrogenase [62] (Scheme 10A). To boost the in situ hydrogen generation (by increasing the amount of functional [Fe-Fe] hydrogenase generated in cells [63]), both iron and casamino acids were added to the reaction media.…”

A Biocompatible Alkene Hydrogenation Merges Organic Synthesis with Microbial Metabolism

“…While most catalysts examined provided no reactivity (Table S4), the Royer palladium catalyst [15] (2.44% palladium on polyethyleneimine (PEI)/silica gel) proved uniquely effective. [16] Using this catalyst, we could double the concentration of substrate and reduce catalyst loading to 8 mol% without impacting conversion (Table 1, Entry 8).…”