Aminolysis reactions. II. Catalysis of esteraminolysis in chlorobenzene. Correlation with hydrogen-bonding ability of catalysts

Abstract

The n-butylaminolysis of p-nitrophenyl acetate in chlorobenzene at 25°follows the rate equation ki,obsi = kz(BA)2 + ks '(B A)(cat.). Dipolar oxygen bases are very effective catalysts of the reaction; A/A-dimethylacetamide is more than twice as effective in catalyzing the reaction as n-butylamine although it is a 1010 times weaker aqueous base. The catalytic abilities of several classes of oxygen and nitrogen compounds correlate with their hydrogenbonding ability to p-fluorophenol in chlorobenzene by the equation log k% = 1.2 log Kf -3.3. This correlation indicates that there is 10-30% proton transfer to the catalyst in the transition state. The results suggest that amides could serve as general base catalysts in enzymes with hydrophobic active sites.

Medium-Controlled Intramolecular Catalysis in the Direct Synthesis of 5′-O-Protected Ribonucleoside 2′- and 3′-Dialkylphosphates

“…[3,4] The reaction of the iron complex salt 1 with p-anisidine provided the tricarbonyliron complex 3 containing a spiro[quinoline-4,1'-cyclohexane] framework (Scheme 1). [3] Through a deuterium labelling Scheme 1. Iron-mediated spiroannelation of p-anisidine.…”

“…This promotes external substitution at the phosphorus atom and provides different phosphoryl transfer mechanisms in the aqueous and organic media. If the solvent characteristics of the enzyme active centers are better mimicked by nonaqueous solvents [3] , these findings may provide relevant information as to the possible role of intramolecular catalysis in enzymatic reactions. This approach also provides a rapid, simple, and cost-effective synthetic pathway to the ribonucleoside 2'-and 3'-dialkylphosphates 13 ± 15.…”

Possibilities of quercetin insertion into poly(N,N-dimethylacrylamide-co-3, 9-divinyl-2, 4, 8, 10-tetraoxaspiro (5.5) undecane) network

“…properties [5][6][7][8]. Aqueous solutions of poly(N,N-dimethylacrylamide) (pDMA), having only two methyl groups and no hydrogen-bonding ability, do not show LCST's below 100°C [9].…”

Lösungsmittelkontrollierte intramolekulare Katalyse bei der direkten Synthese von 5′-O-geschützten Ribonucleosid-2′- und 3′-Dialkylphosphaten

“…Dies fördert die externe Substitution am Phosphoratom und führt zu unterschiedlichen Phosphoryltransfer-Mechanismen in wässrigen und organischen Medien. Wenn das Lösungsmittelverhalten der aktiven Zentren der Enzyme durch nichtwässrige Lösungsmittel besser nachgeahmt wird, [3] , können die Ergebnisse wichtige Informationen liefern, z. B. über die mögliche Rolle der intramolekularen Katalyse bei enzymatischen Reaktionen.…”

“…[2] Wir berichteten vor einigen Jahren über die diastereoselektive eisenvermittelte Spiroanellierung von Arylaminen zu Spirotetrahydrochinolinen. [3,4] Die Reaktion des Eisen-Komplexsalzes 1 mit p-Anisidin liefert den Tricarbonyleisen-Komplex 3 mit einem Spiro[chinolin-4,1'-cyclohexan]-Grundgerüst (Schema 1). [3] Durch Deuterium-Markierung konnte kürzlich gezeigt werden, dass die Eintopf-Spiroanellierung über das intermediäre Tricarbonyleisen-komplexierte 1-Vinyl-4-methoxycyclohexadienyl-Kation 2 verläuft.…”