- A direct transformation of O-silyl groups into O-trichloroacetates. A novel synthetic approach to protein kinase C ligands: 1-Oleoyl-2-acetyl- and 1-hexadecyl-2-acetyl-sn-glycerols
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A fluoride ion-promoted direct esterification of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl (TIPS)-protected glycerol derivatives by means of trichloroacetic anhydride (TCAA), followed by removal of the trichloroacetyl transient protection, provides a new, efficient entry to stereochemically pure 1-oleoyl-2-acetyl- and 1-O-hexadecyl-2-acetyl-sn-glycerols.
- Stamatov, Stephan D.,Kullberg, Martin,Stawinski, Jacek
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- Regioselective and stereospecific acylation across oxirane- and silyloxy systems as a novel strategy to the synthesis of enantiomerically pure mono-, di- and triglycerides
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A trifluoroacetate-catalyzed opening of the oxirane ring of glycidyl derivatives bearing allylic acyl or alkyl functionalities with trifluoroacetic anhydride (TFAA), provides an efficient entry to configurationally homogeneous 1(3)-acyl- or 1(3)-O-alkyl-sn-glycerols. Selective introduction of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl- (TIPS) transient protections at the terminal sites within these key intermediates secures 1(3)-acyl- or 1(3)-O-alkyl-3(1)-O-TBDMS (or TIPS)-sn-glycerols as general bifunctional precursors to 1,2(2,3)-diacyl-, 1(3)-O-alkyl-2-acyl- and 1,3-diacyl-sn-glycerols and hence triester isosters. Incorporation of a requisite acyl residue at the central carbon of the silylated synthons with a subsequent Et3N·3HF-promoted, direct trichloroacetylation across the siloxy system by trichloroacetic anhydride (TCAA), followed by cleavage of the trichloroacetyl group, affords the respective 1,2(2,3)-diacyl- or 1(3)-O-alkyl-2-acyl-sn-glycerols. Alternatively, a reaction sequence involving: (i) attachment of a trichloroacetyl fragment at the stereogenic C2-centre of the monosilylated glycerides; (ii) replacement of the silyl moiety by a short- or long-chain carboxylic acid residue by means of the acylating agent: tetra-n-butylammonium bromide (TBABr)-carboxylic acid anhydride (CAA)-trimethylsilyl bromide (TMSBr); and (iii) removal of the trichloroacetyl replacement, provides pure 1,3-diacyl-sn-glycerols. The TBABr-CAA-TMSBr reagent system allows also a one-step conversion of 1,2-diacylglycerol silyl ethers into homochiral triglycerides with predefined asymmetry and degree of unsaturation. These compounds can also be accessed via a two-step one-pot approach where the trichloroacetyl derivatives of 1,2(2,3)- or 1,3-diacyl-sn-glycerols serve as triester building blocks for establishing the third ester bond at preselected C3(1)- or C2-positions within the glycerol skeleton at the very last synthetic stage. In all instances, the target compounds were produced under mild conditions, in high enantiomeric purity, and in practically quantitative yields. The Royal Society of Chemistry 2007.
- Stamatov, Stephan D.,Stawinski, Jacek
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p. 3787 - 3800
(2008/10/09)
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- Novel chemo-enzymatic synthesis of optically active platelet activating factor
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This paper describes an enantioselective enzymatic synthesis of biologically active platelet activating factor (PAF) starting from chloropyruvic acid.
- Kumar,Bhakuni
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p. 3463 - 3466
(2007/10/02)
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- A Convenient Synthesis of Platelet-Activating Factors and Their Analogues from Chiral Epichlorohydrin
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Two platelet activating factors (PAF) were conveniently prepared from optically active epichlorohydrin via 5 steps in 15-16percent total yield.Four analogues containing oleoyl, propyl, p-trifluoromethylphenoxy, and N,N-dimethyldithiocarbamoyl groups were also prepared.
- Tsuboi, Sadao,Takeda, Shinji,Yamasaki, Yasuhisa,Sakai, Takashi,Utaka, Masanori,et al.
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p. 1417 - 1420
(2007/10/02)
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- Synthesis of 1-O-alkyl-2-O-acetyl-Sn-3-glyceryl-3-phosphoryl choline the enantiomer of platelet activating factor (PAF)
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A novel sterospecific synthesis of biologically active ether-phospholipids (PAF) is reported, involving chemoenzymatic approach.
- Kumar,Shanker
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p. 1763 - 1768
(2007/10/02)
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- Alkyl phospholipid antihypertensive agents in method of lowering blood pressure
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The composition of this invention is 1-O-alkyl-2-acetoyl-sn-glycero-3-phosphocholine, having the ionic structural formula; STR1 wherein R is saturated alkyl having 9-21 carbon atoms, or salts or hydrates of the composition. Preferably R has 13-19 carbon atoms and most preferably R has 15 carbon atoms. The composition of this invention is useful for reducing hypertension in warm-blooded animals, including humans, when administered either orally or by injection or innoculation, e.g., intravenous injection. The composition can be prepared from naturally occurring lipids or synthetically from commercially available material.
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