The oxidation of different phenols , chlorogenic acid (CG), (-)-epicatechin (EC), and (+)-catechin (CA)], catalyzed by apple polyphenol oxidase (PPO), was investigated in the presence of an excess of cysteine. The occurrence of one cysteine addition compound with the two former phenols and two cysteine addition products with the latter phenols was demonstrated by HPLC. In all cases, the formation of addition compound(s) was proportional to the degradation of the phenol. After purification by gel filtration on Trisacryl GF05, the structure of each cysteine conjugate was determined by 1H NMR spectroscopy. After additional 1H homonuclear decoupling and 2D homonuclear COSY experiments, it was shown unequivocally that adduct with MC was 5-S-cysteinyl-3,4-dihydroxytoluene. With CG, the structure was 2-S-cysteinylchlorogenic acid. With catechins, the cysteine was attached on the B ring for the two conjugates. The 2'-position was involved in the first addition compound, whereas it was the 5'-position in the second one. Moreover, the study of UV spectra of the purified compounds allowed the conclusion that the two conjugates of each catechin were formed at the same rate in equivalent amounts.

Further evidence is presented (8) that changes in optical rotation at the D-line of sodium which occur with changes in solvent largely reflect changes in conformational equilibria.Changes in the nuclear magnetic resonance spectrum of 4,4,5,5-tetradeuterio-2-methoxytetrahydropyran and in the rotation of s(+)-2-methoxytetrahydropyran with changes in solvent are interpreted to show that solvents capable of donating a hydrogen to a hydrogen bond have an effect on the magnitude of the anomeric effect which is greater than that resulting from the change in the dielectric constant of the solvent. In the case of methyl 2-deoxypyranosides with the methoxy group in axial orientation, water appears to have an especially profound influence in stabilizing that orientation of the methyl group which brings it into garrche relationship with both the C2-grouping and the anomeric hydrogen; that is, counter to the anomeric effect.The methyl 2-deoxy-e-L-erythro-pentopyranoside was synthesized from di-0-acetyl-L-arabinal by way of an iodomethoxylation. Deuterolysis of the resulting 1,2-trans-acetylated methyl 2-deoxy-2-iodopentosides is shown to proceed in one case with extensive inversion of configuration and with extensive retention in the other case and offers a route to the preparation of 2-deoxy-2-deuterio-erythropentose with a high proportion (> 75%) of the diastereoisomer with the arabino-configuration.

Both the anomers for methyl 2,3-dideoxy-D-glycero-pent-2-enofuranoside were characterized and hydrogenated to the corresppnding methyl 2,3-dideoxy-D-glycero-pentofuranosides. The similar compounds were prepared in the pyranoside ring form but in the L-glycero configuration. The anomeric forms for methyl 3-deoxy-L-erytlrro-pentopyranoside are reported together with a number of their derivatives of interest for the study of solvation effects on conformational equilibria (21). The molar rotations of the deoxy and unsaturated glycosides are discussed as are the conformational properties of the various compounds.Canadian Journal of Chemistry, 47, 4413 (1969) In a previous communication (I), the preparation of the four stereoisomeric methyl 4,6-0-benzylidene-2,3-dideoxy-D-hex-2-enopyranosides was accomplished, in each case, by opening of the epoxide ring of a parent 2,3-anhydro derivative to the corresponding iodohydrin which was treated with either p-toluenesulfonyl (tosyl) or methanesulfonyl (mesyl) chloride in pyridine. We wish to report a modified procedure which allowed the preparation of the anomeric forms both for methyl 2,3-dideoxy-D-glycero-pent-2-enofuranoside (4c and 9c) and for methyl 2,3-dideoxy-L-glycero-pent-2-enopyranoside (17c and 18c).Methyl 5-0-benzoyl-2,3-dideoxy-P-D-glyceropent-2-enofuranoside (9a) was first prepared by reaction of 3,5-di-0-benzoyl-D-erythro-pent-1-enofuranose with methanol (2). The p-D-configuration was later assigned by an alternative synthesis (3,4) involving reduction of methyl 5-0-benzoyl-2,3-di-0-tosyl-P-D-ribofuranoside by the method of Tipson and Cohen (5). The physical constants and nuclear magnetic resonance (n.m.r.) spectrum reported for 9a indicate that this compound was not pure. Also, the n.m.r. signal for Hz was erroneously assigned to HI. It is of interest to note that several 2',3'-unsaturated nucleosides have been prepared (6-10).The 5-0-benzoyl derivative (la) of the readily available methyl 2,3-anhydro-a-D-lyxofuranoside (I 1) was treated with sodium iodide in acetone in the presence of acetic acid and sodium acetate as described previously (1). The spectrum of the sirupy product (2a) required high purity. That the epoxide opening followed the normal course (attack at the 3-position) for a 2,3-anhydrofuranoside (12,13) was established by benzoylation of the iodohydrin 2a to 2c followed by hydrogenolysis to yield crystalline methyl 2,5-di-0-benzoyl-3-deoxy-a-D-theo pentofuranoside (3). This 3-deoxy structure was required since the anomeric proton (singlet at r 4.85) was not appreciably coupled to either of the methylene protons at r 7.35 and 8.05. The quartet at .r 5.35 was assigned to Hz and the spacings indicated 6.5 Hz coupling with the methylene proton (H,) at r 7.35, and 1.6 Hz coupling with that (H,) at r 8.05. Spin decoupling also showed the methylenic protons to be coupled with a signal forming part of a multiplet (H4, H,, and H,,) centered at r 5.5 and assigned to H,.Following the previously reported procedure for the reduction of iodohydrins to olef...

Both the experimental conditions and the kinetic parameters governing the telomerization of hydroxy-functional acryloyl derivatives in the presence of perfluoroalkanethiols were determined with the purpose of synthesizing new amphiphilic telomers with high surface activity for the preparation of stable perfluoro emulsions capable of carrying oxygen in vivo. Several perfluoroalkylated non-ionic telomeric surfactants (FniTACn) were obtained in one step with an average yield of 8O%, by free-radical telomerization of tris(hydroxymethy1)acrylamidomethane in the presence of various perfluoroalkanethiols as chain-transfer reagents. Surface activity, critical micelle concentration and emulsifying capability established the superiority of the FniTACn surfactants over Pluronic@ F68, the major surfactant used presently in the FDA-approved injectable fluorocarbon emulsion: FluosoP. *) Systematic names: N-[tris(hydroxymethyl)methyl]acrylamide (THAM) or -methacrylamide (MTHAM).

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