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13C relaxation studies on side-chain methyl groups in proteins typically involve measurements on (13)CHD(2) isotopomers, where the (13)C relaxation mechanism is particularly straightforward in the presence of a single proton. While such isotopomers can be obtained in proteins overexpressed in bacteria by use of (13)C enriched and fractionally deuterated media, invariably all possible (2)H isotopomers are obtained. This results in a loss of both resolution and sensitivity, which becomes particularly severe for larger proteins. We describe an approach that overcomes this problem by chemical synthesis of amino acids containing a pure (13)CHD(2) isotopomer. We illustrate the benefits of this approach in (13)C side-chain relaxation measurements on the mouse major urinary protein selectively enriched with [gamma(1),gamma(2)-(13)C(2),alpha,beta,gamma(1),gamma(1),gamma(2),gamma(2)-(2)H(6)] valine. Relaxation measurements in the absence and presence of pyrazine-derived ligands suggest that valine side-chain dynamics do not contribute significantly to binding entropy.

The implementation of [13Cα,13C′,15N,2Hα] labelled amino acids into proteins allows the acquisition of high resolution triple resonance experiments. We present for the first time resonance assignments facilitated by this new labelling strategy. The absence of 1JCα,Cβ couplings enables us to measure 1JCα,C′ scalar and 1DCα,C′ residual dipolar coupling constants using modified HNCA experiments which do not suffer from sensitivity losses characteristic for 13C constant time experiments.

NMR dipole-dipole couplings between protein backbone nuclei (1Hα, 13Cα, 15N, 1HN,13C′) offer enormous scope for the rapid determination of protein global folds. Here, we show that measurement of one-bond splittings in the protein backbone is facilitated by use of protein that is selectively isotopically enriched only in the backbone atoms. In particular, 1Hα-13Cα couplings can be measured simply and with high sensitivity by use of conventional heteronuclear single quantum correlation (HSQC) techniques.

D-xylose has been converted into methyl 3-nitro-2,3-dideoxy-D- erythro -furanoside and several analogs which are modified at the 5-position (5-O-benzoyl, 5-O-trimethylacetyl, the uronic acid and methyl uronate ester). These nitro sugars were conveniently hydrogenated to the corresponding amino sugars 1A–1E. The utility of the trimethylacetyl protecting group has been demonstrated for this sequence of reactions.

D-xylose has been converted into methyl 3-nitro-2,3-dideoxy-D- erythro -furanoside and several analogs which are modified at the 5-position (5-O-benzoyl, 5-O-trimethylacetyl, the uronic acid and methyl uronate ester). These nitro sugars were conveniently hydrogenated to the corresponding amino sugars 1A–1E. The utility of the trimethylacetyl protecting group has been demonstrated for this sequence of reactions.

The implementation of [13Calpha,13C',15N,2Halpha] labelled amino acids into proteins allows the acquisition of high resolution triple resonance experiments. We present for the first time resonance assignments facilitated by this new labelling strategy. The absence of 1JCalpha,Cbeta couplings enables us to measure 1JCalpha,C' scalar and 1DCalpha,C' residual dipolar coupling constants using modified HNCA experiments which do not suffer from sensitivity losses characteristic for 13C constant time experiments.

Oxydation electrochimique de l'acide nonyl-7 dioxa-1,4 spiro [4.5] decanecarboxylique en le nonyl-5 hexene-5oate de methyle(I). A partir de (I) synthese du malyngolide

Reaction of the carbonyl compounds (I) with trimethylsilyl trimethylsiloxyacetate (II) in the presence of trimethylsilyl iodide or triflate leads to ring closure, forming the dioxolanones (III).

Synthese par alkylation puis hydrolyse de (methyl-9 [methyl-1' phenyl-1' ethyl]-6 dioxa-1,4 spiro [4.5] decanone-2 chirale

Synthese des acides propyl-3-, isopropyl-3- et phenyl-3 glycerique par ethanolyse des produits d'aldolisation entre des enolates de glycolates et des aldehydes

Oxydation electrochimique de l'acide nonyl-7 dioxa-1,4 spiro [4.5] decanecarboxylique en le nonyl-5 hexene-5oate de methyle(I). A partir de (I) synthese du malyngolide

Reaction of the carbonyl compounds (I) with trimethylsilyl trimethylsiloxyacetate (II) in the presence of trimethylsilyl iodide or triflate leads to ring closure, forming the dioxolanones (III).