Air-Tolerant Direct Thiol Esterification with Carboxylic Acids Using Hydrosilane via Simple Inorganic Base Catalysis

Abstract

Direct thioesterification of carboxylic acids with thiols using nontoxic activation agents is highly desirable. Herein, an efficient and practical protocol using safe and inexpensive industrial waste polymethylhydrosiloxane as the activation agent and K3PO4 with 18-crown-6 as a catalyst is described. Various functional groups on carboxylic acid and thiol substituents can be tolerated by the present system to afford thioesters in yields of 19–100%.

Covalent functionalization of carbon materials with redox-active organic molecules for energy storage

“…54,55 Alternative procedures include the Staudinger ligation, 56 aminocarbonylation of aryl halides, 57 and oxidative amidation of aldehydes. 58 For the functionalization of CBMs, thionyl chloride activation, coupling reagents, or simple heating is employed (Fig. 1b-D).…”

A Recent Progress for the Synthesis of Thiocarboxylates

“…Further efficient synthesis of the polypeptide drug carfilzomib (36) showed the potential application value of this coupling agent. Lin [28] reported an efficient use of industrial waste for direct thioesterification.…”

“…Lin [28] reported an efficient use of industrial waste for direct thioesterification. Using inexpensive polymethylhydrogensiloxane (PMHS) as the activator, 18‐crown‐6 and K 3 PO 4 as the catalyst, various aryl/heteroaryl/alkyl thioesters were obtained in moderate to good yields (Scheme 8).…”

Cu-Catalyzed Oxidative Thioesterification of Aroylhydrazides with Disulfides

“…Over the past three decades, several strategies − have been developed, leading to more than 100 methods for the synthesis of thioesters. Among them, nucleophilic substitution of acyl chlorides/anhydrides with thiols/disulfides, direct coupling of aldehydes with thiols/disulfides, thiocarbonylation of aryl halides with CO, and decarboxylation coupling of α-keto acids with thiols/disulfides have been well developed and are frequently used.…”

“…However, there have only been a few reports demonstrating this strategy. − The underdevelopment of this strategy is due to the thermodynamic disfavor, , in which, owing to the strong conjugation effect, the acyl C–O/or C–N bond of the common carboxylic acids and their derivatives is more stable than the acyl C–S bond of thioesters. Indeed, previous studies have employed substrates that have a decreased activation barrier (Scheme a–c), which leads to the use of specially structured substrates (or in situ formed). ,, For example, Plietker’s work limits to the p -chloro-substituted aryl esters .…”