- Convenient preparation of primary amides via activation of carboxylic acids with ethyl chloroformate and triethylamine under mild conditions
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Primary amides were easily prepared in 22-99% yields from the corresponding carboxylic acids 1 or 5 with NH4Cl via activation with ClCO 2Et and Et3N. The enantiomers of the corresponding primary amides of Cbz-, Boc-, or Fmoc-α-amino acids can be separated by using a chiral column.
- Noguchi, Takuya,Sekine, Masahiro,Yokoo, Yuki,Jung, Seunghee,Imai, Nobuyuki
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p. 580 - 582
(2013/07/05)
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- FATTY ACID ACETYLATED SALICYLATES AND THEIR USES
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The invention relates to Fatty Acid Acetylated Salicylate Derivatives; compositions comprising an effective amount of a Fatty Acid Acetylated Salicylate Derivative; and methods for treating or preventing an inflammatory disorder comprising the administration of an effective amount of a Fatty Acid Acetylated Salicylate Derivative.
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Page/Page column 114-115
(2010/03/04)
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- Cyclic amide derivatives as potential prodrugs II: N- hydroxymethylsuccinimide- / isatin esters of some NSAIDs as prodrugs with an improved therapeutic index
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Ester prodrugs of aspirin la, ibuprofen 1b, naproxen 1c and indomethacin 1d were synthesized using N-Hydroxymethylsuccinimide (HMSI) 3 and N- hydroxymethylisatin (HMIS) 4 as promoieties to reduce their gastrointestinal toxicity and improve bioavailability. Additionally, the kinetics of hydrolysis of the synthesized prodrugs 5a-d and 6a-d were studied at 37°C in non-enzymatic simulated gastric fluid (SGF; hydrochloric acid buffer pH = 1.2); 0.02 M phosphate buffer (pH = 7.4); 80% human plasma and 10% rat liver homogenate. The results indicate higher chemical stability of the ester prodrugs in non-enzymatic SGF (t(1/2) ? 6.5-18.6 h) and rapid conversion to the parent drugs in 80% human plasma (t(1/2) ? 11.4-235 min) as well as in 10% rat liver homogenates (t(1/2) ? 12.0-90.0 min). As a general pattern, the HMSI esters 5a-d revealed higher chemical stability than the corresponding HMIS analogues 6a-d. The pH-rate profile of 5c and 6a indicated maximum stability of the former at pH = 1.2-8.0 and of the latter at pH = 1.2-4.0. The distribution coefficient (D7.4) values of the prodrugs 5a-d, 6a-d and the parent drugs 1a-d in an n-octanol/phosphate buffer (pH =7.4) system indicated enhanced lipophilic properties of the prodrugs. Furthermore, the HMIS ester prodrugs 6a-d are more lipophilic than the corresponding HMSI derivatives 5a-d. In vivo ulcerogenicity studies using scanning electron microscopy on stomach specimens of rats treated with an oral dose for 4 d revealed that the synthesized ester prodrugs are significantly less irritating to gastric mucosa than the parent drugs. These results suggested HMSI and/or HMIS esters possess good potential as prodrugs with an improved therapeutic index for oral delivery of NSAIDs.
- Mahfouz, Nadia M.,Omar, Farghaly A.,Aboul-Fadl, Tarek
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p. 551 - 562
(2007/10/03)
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