Abstract: An idealized model amphiphilic α-helical peptide, cyclo(3-7,10-14,17-21)H-[LysLeuLysGluLeuLysGlu] 3 -OH (peptide 1-1-1), comprising three repeats of a Lys 3 -Glu 7 side-chain bridged heptapeptide, has been synthesized by a generally applicable segment-condensation approach that involves a novel solid-phase cyclization reaction. The linear heptapeptide, Boc-Lys-(2Cl-Z)LeuLys(Trt)Glu(OBzl)LeuLys(2Cl-Z)Glu(oxime resin)-OPac, was built on a p-nitrobenzophenone oxime derivatized polystyrene solid support by standard methods. Circular dichroism spectra indicated that peptide 1-1-1 adopted mostly disordered conformations in aqueous solution, but a high α-helix content was induced in 50% TFE and upon adsorption of peptide 1-1-1 from aqueous solution onto siliconized quartz slides

Abstract: Reducing agents prepared from sodium borohydride (NaBH4), zirconium tetrachloride (ZrCl4), and chiral amino alcohols have been successfully applied to the enantioselective reduction of oxime ethers. Optically active primary amines were obtained in high enantiomeric excess (⩽95% e.e.) with good chemical yield. The extent of asymmetric synthesis was dependent on the solvent, the temperature, the structure of chiral amino alcohol, and the proportions [NaBH4] : [ZrCl4] : [chiral amino alcohol] : [oxime ether].

Abstract: A series of trans-3-alkyl-2-chlorocyclohexanones, (methyl, ethyl, isopropyl, and tert-butyl), have been prepared and shown to exist predominantly in the diequatorial chair conformation except the tert-butyl derivative which prefers a twist-boat. Formation of the oximes and various oxime derivatives (methyloxime, silyloxime) results in a remarkable conformational inversion for the methyl, ethyl, and isopropyl systems. By analysis of vicinal interproton coupling constants it is believed that these compounds exist predominantly in the diaxial chair conformation

Abstract: The N-phenylcarbamate 7, derived from 2-acetamido-2-deoxy-D-gluconhydroximo-1,5-lactone (3) and the analogous N-phenylcarbamate 14, derived from chitobionhydroximo-1,5-lactone (10) have been prepared as potential inhibitors of β-N-acetylglucosaminidases. The unambiguous synthesis of the hydroximo-1,5-lactone 3 involves oxidation of the oxime 1, followed by deprotection with Na/NH3.

Abstract: Conversion of 2,3,5,6-tetra-O-benzyl-D-galactofuranose (19) into its oxime and subsequent treatment with methanesulphonyl chloride gave 2,3,5,6-tetra-O-benzyl-4-O-methylsulphonyl-D-galactonitrile (21). Reductive cyclization by sodium borohydride/cobalt(II) chloride, followed by hydrogenolysis under acidic conditions yielded 1,4-dideoxy-1,4-imino-D-glucitol hydrochloride (11). A similar reaction sequence was used to convert 2,3,5-tri-O-benzyl L-arabinofuranose (23)via the nitrile (25) into 1,4-dideoxy-1,4-imino-D-xylitol hydrochloride (12), and the corresponding D-arabinose derivative (27) gave 1,4-dideoxy-1,4-imino-L-xylitol hydrochloride (13), using the same chemistry.Treatment of 2,3 : 5,6-di-O-isopropylidene-β-D-gulofuranose (31) with hydroxylamine and then methanesulphonyl chloride in pyridine gave 4-O-methylsulphonyl-2,3 : 5,6-di-O-isopropylidene-D-gulononitrile (32), which was converted by treatment with lithium aluminium hydride and subsequent acid hydrolysis into 1,4-dideoxy-1,4-imino-D-allitol hydrochloride (14); similar chemistry in the enantiomeric series gave the L-allitol derivative (15). An analogous reaction sequence was used to convert 2,3 : 5,6-di-O-isopropylidene-α-D-mannofuranose into 4-O-methylsulphonyl-2,3 : 5,6-di-O-isopropylidene D-mannononitrile (38) and thence into 1,4-dideoxy-1,4-imino-D-talitol hydrochloride (16); L-mannonolactone was converted via 2,3 : 5,6-di-O-isopropylidene-α-L-mannofuranose (41) into 1,4-dideoxy-1,4-imino-L-talitol hydrochloride (17).2,3 : 5,6-Di-O-isopropylidene-β-D-allofuranose (45) was converted via its oxime (46) into 4-O-methylsulphonyl-2,3 : 5,6-di-O-isopropylidene-D-allononitrile (47), which on reductive cyclization with lithium aluminium hydride, and subsequent acid hydrolysis, gave 1,4-dideoxy-1,4-imino-D-gulitol hydrochloride (18).

Abstract: The protonation and complex formation equilibria of pyridine-2-carboxaldehyde oxime (1), 1-(2-pyridinyl)elhanone oxime (2) and 6-methylpyridine-2-carboxaldehyde oxime (3), HL, with copper(II) ion were studied in aqueous 0.1 M NaCl solution at 25°C by potentiometric titrations with the use of a glass electrode. Application of the least-squares computer program SUPERQUAD to the experimental data indicated that the following complex species are formed: Cu(HL)2 +, CuL+ (ligand 1), Cu(HL)2 2 + (ligands 1 and 3), Cu(HL)L+ CuL2, Cu3L3OH2+ and Cu3L3O + (or Cu3L3(OH)2 +, ligands 1 and 2). The trinuclear complex Cu3L3OH2 + most probably has a triangular Cu3OH central core. In 1:1 molar ratio of ligand to Cu2+ the trimer exists as the predominating complex around pH 4–6 and gives way to the next deprotonated trimer as the pH is increased.

Abstract: Oximes such as cyclohexanone oxime and benzaldehyde oxime were catalytically transformed into the corresponding lactams in N,N-dimethylformamide solutions of alkylating reagents such as trialkyloxonium salts. Catalyst turnover attained 43 on the basis of the acid used to obtain alkylating reagent. O-Alkyl-N,N-dimethylformamidinium salt was suggested to be a catalyst species.

Abstract: A hydrogenation catalyst composition comprising, as essential components, (a) at least one bis(cyclopentadienyl)transition metal compound represented by general formula (i): and (b) at least one member selected from the group consisting of complex compounds represented by general formulas (ii) and (iii): M²(AlR³R⁴R⁵R⁶) (ii) M²(MgR³R⁴R⁶) (iii) and further comprising, if necessary, (c) at least one polar compound selected from the group consisting of ether compounds, thioether compounds, ketone compounds, sulfoxide compounds, carboxylic acid ester compounds, lactone compounds, amine compounds, amide compounds, nitrile compounds and oxime compounds and/or (d) an alkali compound represented by general formula (iv): M²OR⁷ (iv) The contact of an olefinically unsaturated polymer with hydrogen in the presence of said catalyst composition enables the selective hydrogenation of the olefinic double bonds in said polymer. The thus obtained hydrogenated polymer has excellent weather resistance, heat resistance and oxidation resistance.

Abstract: Publisher Summary In this chapter, gas chromatography–-mass spectrometry (GC-MS)-based method is discussed for the analyses of secondary lipid peroxidation products based on the formation of pentafluorobenzy (PFB) oxime derivatives from 4-hydroxyalkenals. The method improves the extraction efficiency for 4-hydroxyalkenals in biological systems by the formation of an oxime derivative, analogous to the methods used for determination of retinals. An excess of hydroxylamine or O -ethylhydroxylamine has been used to liberate vitamin A aldehydes from Schiff base binding sites. The specific procedure developed in the chapter for the 4-hydroxyalkenals is based on the use of O -(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA-HCI). This reagent forms the O -pentafluorobenzyl oxime derivatives of 4-hydroxyalkenals from free aldehyde or from aldehydes bound to amino groups by Schiff base linkages. The volatility of the 4-hydroxyalkenal oxime is increased by the formation of trimethylsilyl (TMS) ethers of the hydroxyl functions. These derivatives can be detected with high sensitivity by GC-MS with negative ion chemical ionization (NICI)). This approach is inspired by the successful use of PFB ester TMS ether derivatives of hydroxy fatty acids. Isotopically labeled dideuterated analogs of 4-hydroxyalkenals are used as internal standards, which allow 4-hydroxynonenal analyses in quantitative measurements. The method is illustrated in the chapter by data derived from retinas of rats.

Abstract: Reactions of eight oximes, RCH=NOH (1a, R=C 6 H 5 ; 1b, R=4-CH 3 C 6 H 4 ; 1c, R=4-NO 2 C 6 H 4 ; 1d, R=4-CH 3 OC 6 H 4 ; 1e, R=2-CH 3 OC 6 H 4 ; 1f, R=1-naphthyl; 1g, R=C 5 H 11 ; 1h, R=C 4 H 9 ) with thianthrene cation radical perchlorate (Th •+ ClO 4 − ) in acetonitrile under argon were studied. The major product from the oxime in all cases, but of 1d, was the nitrile, RCN

Abstract: A mild procedure for the synthesis of allylic oximes 2 from the corresponding nitro derivatives 1, using carbon disulfide as reducting agent in the presence of wet potassium carbonate and a catalytic amount of a phase-transfer agent, is described

Abstract: Ru3(CO)12 showed high catalytic activity for the deoxygenation of various ketoximes to the corresponding ketimines under carbon monoxide pressure (20 kg/cm2). For the deoxygenation of propiophenone oxime, ethyl phenyl ketimine was obtained in 100% yield. On the other hand, heptanal oxime which was aldoxime was dehydrated under the same reaction conditions to the corresponding nitrile in 32% yield.

Abstract: The reduction of a variety of functional groups with the nickel(II) chloride-zinc system was investigated. This system reduced aldehydes, ketones, olefins, nitriles, oxime, nitro and heterocyclic compounds under mild conditions in good yields. It is of interest that some cases of reduction of ketones afforded the corresponding olefins and the saturated products, and the reduction of nitriles afforded the corresponding primary alcohols with the primary and secondary amines. The selective reduction of olefin and nitro functionalities in some compounds bearing carbonyl, ester and carboxyl functionalities was observed with this system

Abstract: Model studies have been carried out in which the Kaiser-DeGrado procedure for solid-phase synthesis has been combined with the use of reactants with a latent activation feature as a potential route to peptide active esters. The rates of reaction of the 4-(methylthio)phenyl ester of L-phenylalanine with itself, as well as those of a close analogue with tert-butyloxycarbonylglycine bound to a benzophenone oxime functionalized polystyrene resin have been measured in the presence of varying concentrations of the aminolysis catalyst, acetic acid. These studies indicate that under appropriate conditions, it is possible to generate the 4-(methylthio)phenyl esters of suitable peptides, synthesized by solid-phase methods on the oxime-functionalized resin. These peptide esters can then be oxidized to the more strongly electrophilic sulfone derivatives. The preparations of the 4-(methylsulfonyl)phenyl esters of N-tert-butyloxycarbonylglycyl-L-phenylalanine and N-carbobenzyloxy-O-carbobenzyloxy-L-tyrosylglycylglycyl-L-phenylalanine are described as examples of the use of this method of preparing peptide active esters