Bernard T. Golding

Analysis of derivatives of carbohydrates by high-pressure liquid chromatography

Abstract The behaviour of benzoylated derivatives of alditols, monosaccharides, disaccharides, amino sugars, and methyl glycosides in high-pressure liquid chromatography (h.p.l.c.) has been investigated. A system was devised, using the most basic equipment of a single pump and fixed-wavelength u.v. detector, which gave good separations of the components of mixtures of derivatised methyl glycosides. Fractionation of complex mixtures of many of the other benzoylated carbohydrates was achieved in less than 30 min. The 4-nitrobenzoates were less useful for routine analyses.

Specific spin labelling of the Fc region of immunoglobulins

The binding of antigens to the combining site of immunoglobulins, which is in the Fab region, results in the activation of functions which are located in the Fc region [ 1,2] . There has been much interest in the mechanism of this activation, but the only direct evidence for a conformational change in the Fc region on antigen binding comes from studies using circular polarisation of luminescence, e.g. [3] . In these studies additional spectral changes are observed when antigen binds to intact IgG compared with the (Fab’X fragment. However, the evidence for such a conformational change would be more conclusive if the Fc region could be monitored in whole IgG, and this can only be done if a spectroscopic probe can be specifically attached to the Fc region. For example, Gd (III) binds much more tightly to the Fc than to the Fab region of rabbit IgG [4] so that Gd (III) can be used to probe the conformation of the Fc region [5]. The major oligosaccharide present in rabbit IgG is attached to an asparagine residue, which is at position 297 (using the numbering system of the human IgGl myeloma protein Eu) in the C,2 region [6] . In this report we show that this carbohydrate can be specifically spin labelled. The environment of this probe can then be studied by electron spin resonance (ESR).

3,3,3-Trifluoropropan-1-ol and 3,3,3-trifluoropropanal

Abstract Acetoxymercuration of 3,3,3-trifluoropropene leads to 1-acetoxy-3,3,3- trifluoropropene which is hydrolysed to 3,3,3-trifluoropropanol, oxidation of which affords 3,3,3-trifluoropropanal.

Rearrangements of (E,Z)-4-acetyl[17O]oxyhepta-2,5-diene catalysed by Pd0 and PdII: Mechanistic deductions from observations by 17O NMR spectroscopy

Abstract ( E,Z )-4-Acetyl[ 17 O]oxyhepta-2,5-diene [MeCH E =CHCH( 17 OCOMe)CH Z =CHMe] has been synthesised and rearranged under Pd 0 - and Pd II -catalysis. The distribution of 17 O in the products of these rearrangements has been determined by 17 O NMR spectroscopy. With Pd 0 catalyst the product is a 1:1 mixture of MeCH E =CHCH E =CHCH( 17 OCOMe)Me and MeCH E =CHCH E =CHCH(OC 17 OMe)Me formed from an intermediate Pd-coordinated pentadienyl species and 17 O-acetate. With Pd II catalyst the product is MeCH Z =CHCH E =CHCH(OC 17 OMe)Me formed via an intermediate acetoxonium ion.

Proton exchange in dehydromethionine; Synthesis of [C2H3]-L-methionine

Abstract Methyl-labelled methionines can be easily prepared via dehydromethionine (1), which undergoes clean exchange at its methyl group with cat. MeONa/MeO 2 H.

Preparation of N-arylmethylglycinato-bis-(ethane-1,2-diamine)cobalt(III) complexes. Comparison of their exchange reactions at pD 9.7

Abstract The preparation and characterisation of N-arylmethylglycinato bis-(ethane-1,2-diamine)cobalt(III) complexes, where aryl = phenyl (1a) 2-methylphenyl (1b) and naphthyl (1c), are described. In contrast to (1a), exchange of the diastereotopic glycinate methylene protons in (1b) and (1c) in borax buffer (pD 9.7) is shown to proceed non-stereoselectively.

Anaerobic photodecomposition of alkylaquocobaloximes in aqueous solution

The photochemical decomposition of alkylaquocobaloximes in aqueous solution under anaerobic conditions depends critically on the presence of acid. At pH 2, photoreaction is fast and wavelength-independent (ϕ > 0.1 for several alkyl substituents) and involves the production of aqueous cobalt(II) ion and radical intermediates which yield products typical of abstraction and dimerisation reactions. At pH 7, photoreaction is ca. ten-fold less efficient to yield [CoII(Hdmg)2(OH2)2][Hdmg = dimethylglyoximate(1–)] together with an alk-1-ene derived from the axial alkyl ligand.