A short synthetic strategy for the preparation of the α-d-glucopyranosyl-(1→2)-β-d-galactopyranosyl-O-pyridinoline (Glc-Gal-PYD), of the α-d-glucopyranosyl-(1→2)-β-d-galactopyranosyl-5-O-hydroxylysine (Glc-Gal-Hyl) and of their respective epimers, Glc-Gal-epiPYD and Glc-Gal-epiHyl, useful for the analytical evaluation of collagen biomarkers in human sinovium and bone, is reported.
This paper demonstrates that the crystallization of 3β-acetoxy-14α,15α-epoxy-5α-cholest-8-en-7-one from methanol affords the 3β-acetoxy-9α-methoxy-15α-hydroxycholest-8(14)-en-7-one. The structure of this steroid, which shows an apparently anomalous UV absorption maximum, is determined by high field NMR experiments, supporting the coupling constant values assignments and the NOE contacts by a conformational...
A short parallel synthesis of β-d-galactopyranosyl-O-pyridinoline (Gal-PYD), a collagen glycoconjugated cross-link, and of Gal-epiPYD, a (5S)-epimer, useful as internal standard in the analytical evaluation of the natural isomer in human tissue, is reported.
TiF 4 has proven to be the Lewis acid of choice for promoting the biomimetic addition of 2-trimethylsilylmethyl-1,5-dienes to aliphatic aldehydes with concomitant cyclization. 1,3-cis-Disubstituted methylenecyclohexanes are thus produced in good yields and high diastereoselectivity. The reaction appears to proceed via a highly concerted mechanism involving a chair-like transition state.
A straightforward enantioselective synthesis of both enantiomers of the title compounds is described starting from enantiopure methyl (2S,6R)- or (2R,6S)-cis-2-hydroxy-γ-cyclogeraniate. These versatile building blocks are obtained by biomimetic cyclization of methyl (6S)- or (6R)-(Z)-6,7-epoxy-7-methyl-3-(trimethylsilyl)methyl-2-octenoate, respectively. The chiral information was encoded by a highly...
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