1,721,114 research outputs found
Sterol synthesis: Chemical synthesis of 3β-hydroxy-5α-cholest-7-ene-9α-carbonitrile
No full text3beta-Hydroxy-5alfa-cholest-7-ene-9alfa-carbonitrile was obtained via hydrocyanation of 3beta-acetoxy-5alfa-cholest-8-en-7-one by diethylaluminum cyanide. The resulting 9alfa-cyano-7-ketone was reduced with sodium borohydride to 7alfa-hydroxy-compound. These compounds were characterized by infrared, nuclear magnetic resonance, and mass spectral measurement
Mild regeneration of the carboxylic group of amino acid alkyl esters by aqueous methanolic sodium hydrogen carbonate via 5-oxazolidinones
No full textA simple racemization-free procedure allows the regeneration of the carboxylic acid group of amino acid alkyl esters by way of an intermediate 5-oxazolidinone which is hydrolyzed by treatment with sodium hydrogen carbonate in aqueous methano
A practical and simple synthesis of (2S,5R)- and (2S,5S)-5-hydroxylysine and of a related alpha-amino acid required for the synthesis of the collagen cross-link pyridinoline
No full textA four step synthesis of (2S,5R)- and (2S,5S)-5-hydroxylysine using Williams' glycine template methodology for controlling the stereogenicity at the alpha-position is reported. This route offers the possibility for the synthesis of all possible isomers of 5-hydroxylysine and of an important alpha-amino acidic iodohydrin required for the construction of the hydroxylated side chain of the collagen cross-link pyridinoline
A simple modular synthesis of pyridinoline a collagen cross-link of biochemical interest
No full textA simple convergent synthesis of the collagen cross-link pyridinoline starting from glycine is reported
Reduced collagen cross links : the first synthesis of all the possible (2S,2'S)-stereoisomers of 5-hydroxylysinonorleucine and of 5,5'-dihydroxylysinonorleucine in enantiomerically pure form
No full textThe paper reports the first enantioselective synthesis of all the possible collagen reduced cross links as described: ydroxylysinonorleucines I (R1 = R3 = R4 = H, R2 = OH; R1 = R2 = R4 = H, R3 = OH) and dihydroxylysinonorleucines I (R1 = R3 = H, R2 = R4 = OH; R3 = R4 = H, R1 = R2 = OH and R2 = R4 = H, R1 = R3 = OH). The Williams' glycine template methodol. was used both for the introduction of a stereogenic at the ?-position and for an easy protection of the amino acidic functionalities during the synthesis of the dimeric amino acids
A new modular synthesis of deoxypyridinoline, a primary reference material for monitoring bone metabolism
No full textA new modular synthesis of deoxypyridinoline is described which assembles first the 4,5-disubstituted 3-hydroxypyridine ring and then inserts the L-lysine side chain at the pyridine nitroge
A convenient and inexpensive synthesis of labelled methylmalonic and propionic acids: Application to the synthesis of methyl-d(3)-malonic and of propionic-3,3,3-d(3) acids
No full textA synthetic route for obtaining highly pure methylmalonic and propionic acids labelled at the methyl groups is validated by the preparation of methyl-d(3)-malonic and propionic 3,3,3-d(3) acids. The synthesis involves the alkylation of the diethyl allylmalonate with iodomethane-d(3), deallylation of the resulting diethyl allylmethyl-d(3)-malonate by treatment with (eta(2)-propene)Ti(O-i-Pr)(2) and hydrolysis. Decarboxylation of the obtained methyl-d(3)-malonic acid affords propionic-3,3,3-d(3) aci
Cleavage of benzyloxycarbonyl-5-oxazolidinones to α-benzyloxycarbonylamino-α-alkyl esters by alcohols and sodium hydrogen carbonate
No full textThe reaction of benzyloxycarbonyl-5-oxazolidinones with alcohols and sodium hydrogen carbonate to afford the corresponding benzyloxycarbonyl esters is described
Total synthesis of deoxypyridinoline, a biochemical marker of collagen turnover
No full textA convergent synthesis of deoxypyridinoline is described which involves the assembly of a suitably polysubstituted 3-hydroxypyridinium ring starting with fully protected L-lysine and L-glutamic aci
Synthesis of 5 alpha,8 alpha-ethanoergosta-2,6,22-triene-2 'beta-hydroxymethylene-1 'beta-carboxylic acid lactone, a key intermediate for the synthesis of a brassinolide analogue
No full textMetal hydride reduction of the 5 alpha,8 alpha-ethanoergosta-2,6,22-triene-1'beta,2'beta-dicarboxylic acid anhydride prepared by a new route afforded in prevalence the corresponding 4'-lactone, a known steroidal intermediate affording a brassinolide congener by hydroxylation with osmium tetraoxid
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