Supported Palladium‐Gold Catalyzed Carbonylative Methylthioesterification of Aryl Iodides using Oxalic acid and DMSO as CO and CH₃SH Surrogates

Abstract

The polystyrene supported palladium-gold (PdÀ Au@PS) catalyst was prepared and well characterized by HR-TEM, EDX, Elemental Mapping, XPS and P-XRD analysis. The PdÀ Au@PS NPs displayed the superior catalytic activity than their monometallic forms. First time, the catalyst was applied for methylthioesterification reaction of aryl iodides with oxalic acid and DMSO as in situ carbon monoxide (CO) and methyl mercaptan (CH 3 SH) precursor. Yet, there is no report available where DMSO has been applied as CH 3 SH source for methylthioester synthesis. The CH 3 SH and CO are likely to poison the metal catalyst whereas in PdÀ Au@PS catalyst, the beneficial inter-electronic interactions between Pd and Au metals makes the catalyst highly reactive, poisoning resistant and recyclable during the transformation. Moreover, the developed protocol exhibits excellent functional group tolerance for various aryl iodides to delivered the desired products in moderate to very good yields.

Polystyrene Resins: Versatile and Economical Support for Heterogeneous Nanocatalysts in Sustainable Organic Reactions**

“…In addition, the ionic interaction of oxalic acid with the surface of Rh@PS supports maintained the close vicinity and fruitful interaction with the diverse substrates resulted in various derivatives with good product yields (Table 11). In a recent report, Das et al reported a robust and versatile protocol for the synthesis of methyl thioester (MTE) from aryl iodides with oxalic acid and DMSO as in situ carbon monoxide (CO) and methyl mercaptan (CH 3 SH) by deploying bimetallic polystyrene supported Pd-gold (PdÀ Au@PS) catalyst [97] (Scheme 26); DMSO has been successfully applied as CH 3 SH source for the MTE reaction. Additionally, the inter-electronic interactions of Pd and Au metals made the catalyst highly reactive and resistant to poisoning; best yield of desired methyl thioester product attained was found to be 70 % in K 2 CO 3 at 130 °C for 36 h along with a major by product methyl thioether.…”

Recent Advances in Supported Bimetallic Pd–Au Catalysts: Development and Applications in Organic Synthesis with Focused Catalytic Action Study

“…An another 717# ion-exchange resin supported Pd–Au BMC was efficiently applied for the aerobic C–C coupling between primary and secondary alcohols when Pd played active metal role for abstracting the β-H of primary alcohols and transfers this hydride to α,β-unsaturated ketone for obtaining the desired product (Scheme b) . Recently, Das et al reported a polystyrene supported Pd–Au BMC prepared by reduction deposition of palladium and gold metal salts on Amberlite IRA-900 Cl – resin using NaBH 4 as reductant . The resultant Pd–Au BMC was well characterized through HR-TEM, EDS, TEM elemental mapping, XPS, P-XRD, and ICPAES analysis (Figure ), which revealed the bimetallic formation of Pd–Au NPs supported on polystyrene with an average particle size of 5.72 nm and 0.51:0.49 molar ratio of Pd and Au metals, respectively.…”

“…(B) (a) XPS spectra of Pd 3d for Pd–Au@PS and Pd@PS and (b) XPS spectra of Au 4f for Pd–Au@PS and Au@PS; (c) P-XRD diffractogram of polystyrene support (PS), Pd@PS, Pd–Au@PS, and Au@PS. Reproduced with permission from ref . Copyright 2020 Wiley.…”

“…This dominancy of heterogeneous catalysis can be easily seen in various industrial applications such as catalytic production of nitric acid, ethylene, propylene, acetic acid, and methanol, among others, for establishment of high standards of human civilization. Since the past decade, our group has been dedicatedly involved in development of polystyrene supported transition metal (including Pd–Au) NPs as heterogeneous catalysts for various important organic transformations. − The origins of the novel Pd–Au catalysis as bimetallic NPs surface and its heterogeneous catalysts was very well reviewed until 2012. , The present Review highlights the advancements in the past nine years in heterogeneous bimetallic Pd–Au catalysts including their preparation strategies, characterization methods for mechanistic investigations, as well as applications in developing greener, atom economic, and sustainable strategies for different important organic transformation reactions. Because DFT studies reveal a general correlation between the d-band center position and adsorption energy of the bimetallic surface during catalytic transformation, a brief general study also has been included in the current Review for comprehensive understanding of supported Pd–Au BMCs.…”

Palladium supported on MRGO@CoAl‐LDH catalyzed reductive carbonylation of nitroarenes and carbonylative Suzuki coupling reactions using formic acid as liquid CO and H2 source

“…[29,30] However, the usage of gaseous CO led to the restriction in applications of carbonylative coupling reactions in laboratories because CO is colorless, toxic, odorless, and flammable. Various carbonyl surrogates such as transition-metal carbonyls, [31,32] acetic formic anhydride, [33] chloroform, [34] N-formylsacchrin, [35] oxalic acid, [36] and formic acid have been applied for carbonylative Suzuki coupling reaction. [37] In this work, formic acid is used as a source of carbonyl because of special properties as mentioned earlier.…”