Additive Effect of N-Heteroaromatics on Transesterification Catalyzed by Tetranuclear Zinc Cluster

Abstract

A catalytic amount of 4-dimethylaminopyridine showed drastic additive effects on transesterification catalyzed by the μ 4 -oxo-tetranuclear zinc cluster Zn 4 (OCOCF 3 ) 6 O, enhancing the catalytic activity by more than 15-fold. The new catalyst system facilitates transesterification of less reactive sterically demanding esters and alcohols.

The effect of side-chain substitution on the aggregation and photovoltaic performance of diketopyrrolopyrrole-alt-dicarboxylic ester bithiophene polymers

“…Monomers M1-M3 were obtained in high yield and high purity via the zinc catalysed transesterication reaction of 1 using an excess of the corresponding alcohol. 36,37 Precursor 1 was synthesized via a previously reported procedure. 38 Monomers M4 and M5 were obtained by functionalizing 3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dione (2) with the corresponding alkyl-bromide side-chain followed by lithiation and stannylation.…”

Zinc‐Catalyzed Amide Cleavage and Esterification of β‐Hydroxyethylamides

“…Zn(OTf) 2 diethylcarbonate (3 d) 18 61 12 [c] Zn(OTf) 2 diethylcarbonate (3 d) 18 70 13 [c] Zn ( (3 h). Although we previously demonstrated that amines and N-heteroaromatic compounds increased the catalytic activity of the zinc cluster for transesterification, [9] such positive effects of amines were not observed in this transformation of an amide into an ester (see the Supporting Information). The chemical yield of the desired butyl ester 2 a was limited to a maximum yield of approximately 20 % when using any zinc complex, thus suggesting that this catalytic reaction is reversible.…”

Zinc‐Catalyzed Amide Cleavage and Esterification of β‐Hydroxyethylamides

“…Among the mononuclear zinc precursors examined, Zn(OTf) 2 was the best catalyst (entries 4 and 7) for reactions conducted with a shorter reaction time (3 h). Although we previously demonstrated that amines and N‐heteroaromatic compounds increased the catalytic activity of the zinc cluster for transesterification,9 such positive effects of amines were not observed in this transformation of an amide into an ester (see the Supporting Information).…”