Widely Useful DMAP-Catalyzed Esterification under Auxiliary Base- and Solvent-Free Conditions

Abstract

With regard to atom economy and E-factor, catalytic condensation of carboxylic acids with equimolar amounts of alcohols is the most desirable. Although several highly active dehydration catalysts have been reported, more efficient alternatives are still strongly needed because the dehydrative esterification of tertiary alcohols, phenols, acid-sensitive alcohols, amino acids, and hardly soluble alcohols has never proceeded satisfactorily. Here we report new insights into the classical DMAP-catalyzed acylation of alcohols: surprisingly, only a 0.05-2 mol % of DMAP can efficiently promote acylation of alcohols with acid anhydrides under auxiliary base- and solvent-free conditions to give the corresponding esters in high yields. Furthermore, we achieved the recovery and reuse of commercially available polystyrene-supported DMAP without using any solvents. These serendipitous findings provide widely useful and environmentally benign esterification methods, which might be more practical and reliable than catalytic dehydrative condensation methods, in particular, for the less reactive alcohols which hardly condense with carboxylic acid directly.

Antileishmanial Lead Structures from Nature: Analysis of Structure-Activity Relationships of a Compound Library Derived from Caffeic Acid Bornyl Ester

“…[33]. (27) Propanoic acid (700 mg, 4.66 mmol) was dissolved in NEt 3 (3.2 mL, 5 eq.) and cooled in an ice bath.…”

Zncl2@MWCNTs nanocomposite as an efficient and reusable catalyst for direct regioselective ortho C-acylation of phenolic compounds under solvent-free and microwave conditions

“…The ortho C-acylated phenols are also important synthons in organic chemistry (1)(2)(3)(4)(5). They serve as protecting groups (6), polyfunctional molecules such as nucleosides, carbohydrates and peptides (7), or modified peptides such as isoesters (8) and steroids (9)(10)(11)(12).…”

M(acac)n Covalently Anchored onto Amine Functionalized Silica: Highly Efficient and Recyclable Heterogeneous Catalysts for the Acetylation of Amines, Phenols and Alcohols Under Solvent-Free Conditions

“…In order to overcome above problems, development of green procedures using heterogeneous catalysts under solvent-free conditions has aroused great interest in recent years [21] since organic reactions run under solvent-free conditions have added advantages of formation of cleaner products and avoidance of toxic or volatile solvents. Heterogeneous catalytic materials play a very important role in the selective protection of functional groups, thus leads to economically advantageous, environmentally friendly and also improved process conditions for large scale synthesis [22][23][24][25][26].…”