Search results for "DISCOVERY"

Enzymatische hydrolyse hydrophiler ester durch lipasen - eine milde carboxydeblockierung von peptiden und glycopeptiden

1993

Abstract The markedly hydrophilic 2-(N-morpholino)ethyl (MoEt) esters of protected peptides and glycopeptides are selectively and efficiently cleaved by lipases in water/acetone (10:1) at pH 7.

2019

Molecular complexes between glycolic acid and nitrogen were studied in a low-temperature argon matrix with FTIR spectroscopy, and supported by MP2 and BLYPD3 calculations. The calculations indicate 11 and 10 stable complex structures at the MP2 and BLYPD3 levels of theories, respectively. However, only one hydrogen-bonded complex structure involving the most stable SSC conformer of glycolic acid was found experimentally, where the nitrogen molecule is bound with the carboxylic OH group of the SSC conformer. The complex shows a rich site structure variation upon deposition of the matrix in different temperatures and upon annealing experiments, which provide interesting prospects for site-sel…

Synthesis of various natural 8,12-elemanolides from artemisin

1989

Abstract This paper describes the chemical transformations of artemisin into various natural 8,12-elemanolides.

New simple convergent synthetic method for benzyl aryl ether dendritic structures

2001

Abstract Phenolic benzyl aryl ether based dendrons with an ester periphery are easily prepared by convergent strategy through hydroxy substituted methyl benzoates and easily attainable benzoyl protected 3,5-bis(bromomethyl)phenol. The dendrons obtained can afford dendronized styrenes.

Deprotonation of Fluoro Aromatics Using Lithium Magnesates.

2004

Abstract 3-Fluoropyridine was deprotonated on treatment with 1/3 equiv of Bu 3 MgLi in THF at −10 °C. The lithium arylmagnesate formed was either trapped with electrophiles or involved in a palladium-catalyzed cross-coupling reaction with 2-bromopyridine. The use of a less nucleophilic lithium-magnesium-dialkylamide, (TMP) 3 MgLi, allowed the reaction of 3-fluoroquinoline, giving the 2,2′-dimeric derivative. 2-Fluoropyridine and 2,6-difluoropyridine were deprotonated using 1/3 equiv of the highly coordinated magnesate Bu 4 MgLi 2 in THF at −10 °C in the presence of a substoichiometric amount of 2,2,6,6-tetramethylpiperidine. 1,3-Difluorobenzene reacted similarly when treated with Bu 3 MgLi;…

A theoretical study of the selectivity for the domino [5+2]/[4+2] cycloadditions of γ-pyrones bearing tethered alkenes with substituted 1,3-butadienes

2001

Abstract Selectivity of the domino [5+2]/[4+2] cycloaddition reactions of a β-silyloxy-γ-pyrone bearing a tethered alkene with two substituted 1,3-butadienes have been theoretically studied at the B3LYP/6-31G∗//AM1 and B3LYP/6-31G∗ computational levels. Analysis of these results allow explaining the regio, stereo and chemoselectivity observed experimentally at these domino reactions. Selectivity outcome is reproduced by these calculations.

4-(2-Adamantyl)thiosemicarbazone

1984

Aus der Umsetzung von 4-(2-Adamantyl)thiosemicarbazid (1) mit den Carbonylverbindungen 2a-d gehen die 4-(2-Adamantyl)thiosemicarbazone 3a-d hervor. Die Startkomponente 1 ist aus 2-Aminoadamantan (4) uber das (2-Adamantyl)-isothiocyanat (5) zuganglich. Verbindung 5 und Vertreter des Strukturtyps 3 vermogen antivirale, antimykotische und antipyretische Wirkung auszuuben. Antiviral Agents, XXIV: 4-(2-Adamantyl)thiosemicarbazones Reactions of 4-(2-adamantyl)thiosemicarbazide (1) with the carbonyl compounds 2a-d yield the 4-(2-adamantyl)thiosemicarbazones 3a-d. The starting material 1 is accessible from 2-aminoadamantane (4) via 2-adamantyl isothiocyanate (5). Compound 5 and representatives of t…

Benzimidazoles as NMDA Glycine-Site Antagonists: Study on the Structural Requirements in 2-Position of the Ligand

2000

A series of different substituted benzimidazole derivatives has been synthesized and evaluated for the ability to displace [3H]MDL-105,519 to rat cortical membranes. Two benzimidazole-2-carboxylic acids 9 b and 9 c, in this substitution pattern not yet described as glycine antagonists, showed IC50 values of 0.89 microM (9 b) and 38.0 microM (9 c). Replacement of the carboxylate function in 2-position by a sulfonic acid moiety appreciably increased solubility, but decreased the affinity giving evidence for the strong need of the carboxylate group within the ligand. Further structure-activity studies using benzimidazole-2-one derivatives with an acetic acid moiety adjacent to a ring nitrogen …

Struktur-Wirkungsbeziehungen bei Histaminanaloga, 14. Mitt. 4-Aminomethyl-benzimidazole und 9-Amino-naphth[1,2-d]imidazole

1977

Es wird die Darstellung der bicyclischen Histaminanaloga 4-Aminomethyl-benzimidazol (3a) und 4-Aminomethyl-4,5,6,7-tetrahydro-benzimidazol (3b) sowie der tricyclischen Analoga 9-Amino-6,7,8,9-tetrahydro-naphth[1,2-d]imidazol (6b) und 9-Amino-4,5,5a,6,7,8,9,9a-octahydro-naphth[1,2-d]imidazol (6c) beschrieben. 4-(Aminomethyl)benzimidazoles and 9-Aminonaphth[1,2-d]imidazoles Syntheses of the bicyclic histamine analogues 4-(aminomethyl)benzimidazole (3a) and 4-aminomethyl-4,5,6,7-tetrahydrobenzimidazole (3b) and of the tricyclic analogues 9-amino-6,7,8,9-tetrahydronaphth[1,2-d]imidazole (6b) and 9-amino-4,5,5a,6,7,8,9,9a-octahydronaphth[1,2-d]-imidazole (6c) are described.

Total synthesis of the monoterpenes (−)-mintlactone and (+)-isomintlactone

1992

Abstract The first total stereodirected synthesis of the monoterpenes (−)-mintlactone and (+)-isomintlactone from the same chiral starting product is described. A stereoselective, radical-mediated ring closure was the key step in both syntheses.