Electrochemical Oxidative Oxydihalogenation of Alkynes for the Synthesis of α,α-Dihaloketones

Abstract

An electrochemical oxydihalogenation of alkynes has been developed for the first time. Using this sustainable protocol, a variety of α,α-dihaloketones can be prepared with readily available CHCl3, CH2Cl2, ClCH2CH2Cl, and CH2Br2 as the halogen source under electrochemical conditions at room temperature.

Electrochemical Oxidative Functionalization of Arylalkynes: Access to α,α‐Dibromo Aryl Ketones

“…In particular, electrochemical C−X formation is a useful way to construct electrophiles, which can be utilized for further synthetic manipulations [15a,16] . Recently, Huang's group reported the electrochemical oxydihalogenation of arylalkynes using organic halides as the halogen sources, including CHCl 3 , CH 2 Cl 2 , ClCH 2 CH 2 Cl, and CH 2 Br 2 (Scheme 2b) [17] . Last year, our group reported a series of electrochemical halogenation reactions using NaX/HX as the halogen sources [18] .…”

Synthetic Routes Towards the Synthesis of Geminal α‐Difunctionalized Ketones

“…The application of alkynes towards the synthesis of gem ‐functionalized ketones is amongst some of the most studied protocols in this field of synthetic chemistry (general approach, Scheme 21), and arguably one of the most studied areas involves the oxyhalogenation of terminal (and internal alkynes). To access dihalogenated ketones, transition metal catalysts such as molybdenum have been employed, [53] micellar‐enabled photo‐assisted oxyhalogenation of alkynes in water can be conducted, [54] utilizing electrochemical methods to affect the oxyhalogenation reaction, [55] the use of UV light under photo‐aerobic oxidative conditions, [56] along with photoredox oxyhalogenation with phenylacetylene in the absence of catalyst, [57] are just a few methods amongst numerous others to access such desirable molecules.…”

Dihalooxygenation of Alkynes and Alkynols: Preparation of 2,2-Dihaloketones and gem-Dihalolactols

“…1 However, only few methods have been reported for the preparation of these compounds which were summarized in Scheme 1. The methods for the synthesis of 2,2-dihaloketone included dihalogenative coupling reaction between esters and organoborons, 2 enolatebased halogenation of ketones, 3 nucleophilic substitution of esters, 4 and dihalooxygenation of alkynes [5][6][7][8] (Scheme 1A). Among these protocols, dihalooxygenation of alkynes was perhaps the most common method as alkyne served as an excellent functional group for various notable transformations.…”

“…using water as the solvent and haloform or dihaloethane as the source of halogen to convert alkynes to 2,2-dihaloketones. 5 The products were obtained in low to mostly moderate yields in almost entirely terminal alkyne substrates (R 1 = H, Scheme 1B). A photochemical approach using blue LEDs was also developed by Jiang and colleagues.…”