Synthesis of 3-benzylidenetetrahydrofurans: Tf2O-catalyzed hydroxylation/cyclization of cyclopropanemethanols with DMSO

KF-catalyzed direct thiomethylation of carboxylic acids with DMSO to access methyl thioesters

With dimethyl sulfoxide (DMSO) as the methylthio source, a KF-catalyzed strategy was employed for the direct thiomethylation of carboxylic acids with DMSO for the preparation of methyl thioesters. In this process, a wide range of methyl thioesters were obtained in moderate to excellent yields. This novel strategy features the first use of DMSO as a methylthiolating agent for the construction of methyl thioesters, transition metal-free conditions, inexpensive reagents, easy workup, broad substrate scope and sustainability. Additionally, this procedure can be readily scaled up to a gram scale.

Rapid Access to Arylated and Allylated Cyclopropanes via Brønsted Acid-Catalyzed Dehydrative Coupling of Cyclopropylcarbinols

A regioselective protocol for the synthesis of cyclopropyl derivatives that relies on Brookhart acid-catalyzed dehydrative coupling over substituted cyclopropylcarbinols without rearrangement is reported herein. The reactions proceed promptly at 25 °C with only 2.0 mol % catalyst loading and produce the cyclopropyl derivatives in excellent yields. This method is well tolerated with a vast range of cyclopropylcarbinols including aliphatic cyclopropylcarbinols, where no elimination product was obtained, demonstrating the protocol's utility. Further, the Hammett correlation suggested the formation of a cyclopropylcarbinyl cation followed by a coupling reaction. An extremely effective gram-scale reaction has also been demonstrated with a high turnover number.

DMSO as a C1 Source for [2 + 2 + 1] Pyrazole Ring Construction via Metal-Free Annulation with Enaminones and Hydrazines

A cascade reaction between enaminones, hydrazines, and dimethyl sulfoxide (DMSO) for the synthesis of 1,4-disubstituted pyrazoles catalyzed by molecular iodine in the presence of Selectfluor has been realized. DMSO plays a dual role as the C₁ source and the reaction medium. In addition, the synthesis of 1,3,4-trisubstituted pyrazoles using aldehydes as alternative C₁ building blocks has also been achieved.