@article {1195, title = {High yielding synthesis of 3a-hydroxypyrrolo[2,3-b]indoline dipeptide methyl esters: Synthons for expedient introduction of the hydroxypyrroloindoline moiety into larger peptide-based natural products and for the creation of tryptathionine bridges}, journal = {Journal of Organic Chemistry}, volume = {70}, number = {21}, year = {2005}, note = {ISI Document Delivery No.: 971SRTimes Cited: 12Cited Reference Count: 33}, month = {Oct}, pages = {8424-8430}, type = {Article}, abstract = {This work describes a rapid and high yielding oxidation of 14 tryptophanylated amino acid methyl esters to the corresponding 3 alpha-hydroxypyrrolo[2,3-b]indoline (Hpi) amino acids with generally facile separation of syn-cis and anti-cis diastereomers. Structural X-ray diffraction data are presented for both diastereomers of Tr-Hpi-Gly-OMe, which allow for a putative assignment of the other 13 pairs of diastereomers reported herein, based on correlations with H-1 NMR chemical shifts. Selective and high yielding deprotection at either the N or C terminus is described, allowing the Hpi motif to be introduced efficiently into potential targets with minimal protecting group manipulation. Two tripeptides containing Hpi and cysteine were prepared and treated with acid in the Savige-Fontana reaction to produce a cyclic tryptathionine linkage, characteristic of both amatoxins and phallotoxins.}, keywords = {ANALOGS, ASYMMETRIC EPOXIDATION METHOD, CONFIGURATION, CONFORMATION, CYCLIZATION, CYSTEINE SULFHYDRYL-GROUPS, DERIVATIVES, HIMASTATIN, OXYGENATION, TRYPTOPHAN}, isbn = {0022-3263}, url = {://000232405500022}, author = {May, J. P. and Fournier, P. and Pellicelli, J. and Patrick, B. O. and Perrin,David M.} } @article {4571, title = {Towards inhibition of yellowing of mechanical pulps. Part III. Hydrogenation of milled wood lignin}, journal = {Journal of Pulp and Paper Science}, volume = {25}, number = {9}, year = {1999}, note = {ISI Document Delivery No.: 235YETimes Cited: 10Cited Reference Count: 18}, month = {Sep}, pages = {312-317}, type = {Article}, abstract = {Oxygenation of hexadecacarbonylhexarhodium(0), Rh-6(CO)(16), in dimethylformamide (DMF) generates nn active catalyst, formulated as Rh-6(mu(3)-O)(4)(OH)(12) (DMF)(n), far the hydrogenation of the aromatic rings of milled wood lignin at similar to 20 degrees C under I atm H-2 in aqueous methyl cellosolve. Partial hydrogenation of the aromatic rings in lignin was confirmed by H-1 NMR spectroscopy. The ability of the catalyst to hydrogenate the lignin model compound 2-methoxy-4-propylphenol is critically dependent on the reaction medium: hydrogenation proceeds faster in aqueous ethanol than in aqueous dioxane, aqueous methyl cellosolve or anhydrous ethanol while no hydrogenation occurs in aqueous DMF.}, keywords = {aromatic compounds, CATALYSTS, CATALYTIC-HYDROGENATION, COMPOUNDS, HYDROGENATION, INHIBITION, lignin model, milled wood lignins, model compounds, OXYGENATION, rhodium compounds, yellowing}, isbn = {0826-6220}, url = {://000082570800002}, author = {Hu, Thomas Q. and James, Brian R. and Wang, Y.} } @article {4571, title = {Towards inhibition of yellowing of mechanical pulps. Part III. Hydrogenation of milled wood lignin}, journal = {Journal of Pulp and Paper Science}, volume = {25}, number = {9}, year = {1999}, note = {ISI Document Delivery No.: 235YETimes Cited: 10Cited Reference Count: 18}, month = {Sep}, pages = {312-317}, type = {Article}, abstract = {Oxygenation of hexadecacarbonylhexarhodium(0), Rh-6(CO)(16), in dimethylformamide (DMF) generates nn active catalyst, formulated as Rh-6(mu(3)-O)(4)(OH)(12) (DMF)(n), far the hydrogenation of the aromatic rings of milled wood lignin at similar to 20 degrees C under I atm H-2 in aqueous methyl cellosolve. Partial hydrogenation of the aromatic rings in lignin was confirmed by H-1 NMR spectroscopy. The ability of the catalyst to hydrogenate the lignin model compound 2-methoxy-4-propylphenol is critically dependent on the reaction medium: hydrogenation proceeds faster in aqueous ethanol than in aqueous dioxane, aqueous methyl cellosolve or anhydrous ethanol while no hydrogenation occurs in aqueous DMF.}, keywords = {aromatic compounds, CATALYSTS, CATALYTIC-HYDROGENATION, COMPOUNDS, HYDROGENATION, INHIBITION, lignin model, milled wood lignins, model compounds, OXYGENATION, rhodium compounds, yellowing}, isbn = {0826-6220}, url = {://000082570800002}, author = {Hu, Thomas Q. and James, Brian R. and Wang, Y.} }