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Query: UMLS:C0012739 (
disseminated intravascular coagulation
)
8,673
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Perloza beaded cellulose was functionalised by a cyanoethylation/reduction procedure to give aminopropyl Perloza. Fmoc-amino acids were anchored to aminopropyl Perloza beaded cellulose via the TFA labile 4-oxymethylphenoxyacetyl (HMPA) linker. Using Fmoc-aminoacyl-4-oxymethylphenoxyacetyl-2,4-dichloro-phenyl esters, all 20 amino acids were anchored at substitution levels ranging from 0.37 to 0.65 mmol/g. Fmoc-amino acids were also anchored using the peptide-amide linker 4-[(R,S)-1-[1-(9H-fluoren-9-yl)-methoxycarbonylamino - (2',4'-dimethoxybenzyl]phenoxyacetic acid. The Fmoc-aminoacyl resins were used for SPPS using Fmoc chemistry. SPPS was carried out using either an LKB Biolynx 4175 low-pressure pumped column continuous-flow peptide synthesiser or an ABI 430A automated vortexing batchwise instrument. Comparison of peptides made using each synthesiser showed little difference in quality of the crude peptides. Different Fmoc-amino acid activation methods (
DIC
/HOBt/
DMF
, HBTU,
DIC
/HOBt/DCM) were found to be equally useful with Perloza. Peptides were cleaved using TFA plus scavengers; however, the TFA-swollen resin was not readily separated from the TFA/peptide solution by simple filtration. Therefore alternative cleavage workup procedures were used with Perloza. Peptides were purified by HPLC and characterised by HPLC and amino acid analysis, and in some cases by FAB-MS. Successful syntheses ranged from 5 to 34 amino acids in length. Some of the peptides were also synthesized using a polystyrene support and standardised (ABI Fastmoc) SPPS protocols. The crude cleaved peptides from each synthesis were compared by HPLC analysis. The overall aim of our work with Perloza is synthesis of resin-bound peptide ligands for affinity chromatography and antibody generation.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Fmoc SPPS using Perloza beaded cellulose. 792 85
The preparation of 3,4,5-substituted 8-carboxamido-1,5-benzodiazepin-2-ones using a solid-phase synthetic method is described. 4-Fluoro-3-nitrobenzoic acid is tethered to a solid support via the acid group. Aromatic substitution of the aryl fluoride with either an alpha- or beta-substituted beta-amino ester is carried out in the presence of DIEA in
DMF
. The reduction of the aryl nitro group is accomplished in the presence of SnCl(2).H(2)O. Hydrolysis of the ester is carried out in the presence of a heterogeneous mixture of 1 N NaOH/THF (1:1). The resulting aniline acid is cyclized to form the benzodiazepinone skeleton with
DIC
and HOBt. Selective alkylation at the N-5 position of the benzodiazepinone is accomplished with alkyl halides in the presence of K(2)CO(3) in acetone. The desired products are cleaved from solid supports and obtained in 46-98% isolated yields.
...
PMID:Solid-Phase Synthesis of 3,4,5-Substituted 1,5-Benzodiazepin-2-ones. 1167 2
3-Acylmethylidene-3,4-dihydroquinoxalin-2(1
H
)-ones are compounds which possess a wide range of physical and pharmaceutical applications. These compounds can be easily prepared by cyclocondensation of
o
-phenylenediamines and aroylpyruvates. Unsymmetrically substituted
o
-phenylenediamines can be obtained form regioisomeric mixtures of 3,4-dihydroquinoxalin-2(1
H
)-ones. It is often quite difficult to get a pure regioisomer and determine its structure without controlling the reaction selectivity and exploitation of complex NMR techniques (HSQC, NOESY, HMBC). This article examines the regioselectivity of the cyclocondensation between six monosubstituted
o
-phenylenediamines (-OMe, -F, -Cl, -COOH, -CN, -NO
2
) and the derivatives of
p
-chlorobenzoylpyruvate (ester or acid) which we studied. Six regioisomeric 3,4-dihydroquinoxalin-2(1
H
)-one pairs were selectively prepared and characterised. Based on our experiences, a simplified methodology for determining the structure of the regioisomers was proposed. We developed two general and highly selective methodologies starting from the same
o
-phenylenediamines and activated 4-chlorobenzoylpyruvates (ester or acid) enabling switching of 3,4-dihydroquinoxalin-2(1
H
)-one regioselectivity in a predictable manner. For comparison, all regioselective cyclocondensations were performed with the same standardized conditions (
DMF
, rt, 3 days), differing only by the additives
p
-TsOH or HOBt/
DIC
(hydroxybenzotriazole/
N
,
N'
-diisopropylcarbodiimide). Both selected methods are simple, general and highly regioselective (72-97%). A mechanism for the regioselectivity was also proposed and discussed. This study can be used as a guide when choosing the most optimal reaction conditions for the synthesis of the desired 3,4-dihydroquinoxalin-2(1
H
)-one regioisomers with the best selectivity. The demonstrated methodologies in this article may also be applied to differently substituted 3,4-dihydroquinoxalin-2(1
H
)-ones in general, which could expand the synthetic impact of our results.
...
PMID:Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1
H
)ones from
o
-phenylenediamines and aroylpyruvates. 2878 1
