5-membered heterocyclic compounds, processes for preparing them and
申请人:Dr. Karl Thomae GmbH
公开号:US05463071A1
公开(公告)日:1995-10-31
Compounds of the formula ##STR1## wherein X.sub.1 to X.sub.5 are as defined herein, the tautomers, the stereoisomers including the mixtures thereof and the salts thereof, particularly the physiologically acceptable salts thereof with inorganic or organic acids or bases. The compounds are useful for inhibiting undesirable cell aggregation.
Expeditious Access to Unprotected Racemic Pyroglutamic Acids
作者:Jerry Isaacson、Cynthia B. Gilley、Yoshihisa Kobayashi
DOI:10.1021/jo0700225
日期:2007.5.1
A series of biologically intriguing pyroglutamicacids were synthesized in racemic form by employing indole−isonitrile and ammonium acetate in the Ugi 4-center-3-component reaction of γ-ketoacids.
Synthesis of 5-aminolevulinic acid with nontoxic regents and renewable methyl levulinate
作者:Yuxia Zai、Yunchao Feng、Xianhai Zeng、Xing Tang、Yong Sun、Lu Lin
DOI:10.1039/c9ra01517e
日期:——
Synthesis of 5-aminolevulinic acid (5-ALA) was presented with novel bromination of biobased methyl levulinate (ML), followed by ammoniation and hydrolysis. Copper bromide (CuBr2) was employed as the bromination reagent with higher selectivity and activity instead of the conventional liquid bromine (Br2). 5-ALA was obtained in a high yield (64%) and purity (>95%) by optimum design, which is of great
Variation in the regioselectivity of levulinic acid bromination in ionic liquids
作者:Alexander G. Zavozin、Natalya E. Kravchenko、Nikolay V. Ignat’ev、Sergei G. Zlotin
DOI:10.1016/j.tetlet.2009.11.097
日期:2010.1
The reaction of levulinicacid and its esters with bromine in ionic liquids results in the formation of 3-bromo derivatives as the major products and not the 5-bromo substituted isomers, which are typically formed in organic solvents. The bromination of levulinicacid in ionic liquids in the presence of urea leads to the formation of 5-bromolevulinic acid.
Ionic Liquids—Advanced Reaction Media for Organic Synthesis
作者:Nikolai V. Ignat'ev、Michael Schulte、Karsten Koppe、Peter Barthen、Sergei G. Zlotin、Nina N. Makhova、Aleksei B. Sheremetev、Anabela A. Valente
DOI:10.1080/10426507.2010.538557
日期:2011.5.1
Abstract The advantages in the application of ionicliquids as reaction media in organicsynthesis, i.e., in the preparation of chromane derivatives, substituted pyrazines, 4-aminofuran-2(5H)-ones, or in bromination of Levulinic acid or dehydration of alcohols, saccharides, and polysaccharides, have been demonstrated on several examples. Ionicliquids with Brønsted acidity have been shown to possess