Synthesis of α,α‐Dichloroketones through Sequential Reaction of Decarboxylative Coupling and Chlorination

Abstract

2,2‐Dichloro‐1,2‐diarylethanones were synthesized from diarylalkynes and trichloroisocyanuric acid. The reaction was conducted in CH3CN/H2O at room temperature for 12 h. In addition, the desired 2,2‐dichloro‐1,2‐diarylethanones could be prepared from aryl bromides and propiolic acid through sequential Pd‐catalyzed decarboxylative coupling and chlorination. This method showed moderate to good yields and good tolerance toward functional groups such as chlorides, bromides, aldehydes, and ketones.

Tandem Deoxygenative Geminal Fluorosulfonimidation of 1,2-Diketones via Formal N–F Insertion Enabled by Dealkylation-Resistant Phosphoramidite

“…Unfortunately, no desired product 12 was detected from the reaction with N -chlorophthalimide (NCP); instead, geminal dichloride 13 was obtained unexpectedly (Scheme 9 A). 20 On the other hand, α-chloroamine 14 was produced by N -chlorosuccinimide (NCS), but the yield was low, and again 13 was observed (Scheme 9 B). 21 As seen previously from the geminal chlorofluorination, 7a chlorenium is not appropriate here, either.…”

Synthetic Routes Towards the Synthesis of Geminal α‐Difunctionalized Ketones

“…Whilst the aforementioned work on the halogenation of alkynes to access dibromoketones was extensive, the dichlorinated version was less documented in this work. A subsequent article in 2018 by Lee, Kim and co‐workers addressed this issue by accessing various dichloroketone products 117 through reacting diarylalkynes and trichloroisocyanuric acid (TCCA) by decarboxylative coupling and chlorination reactions [63] . Initially, the chlorination reaction of diarylalkynes 114 was carried out using TCCA and an excess amount of water as reactant in acetonitrile as reaction solvent at room temperature – this developed protocol afforded α,α‐dichloroketones 117 in yields ranging between 43 %–91 % (Scheme 25a).…”

Modular and Chemoselective Strategy for Accessing (Distinct) α,α‐Dihaloketones from Weinreb Amides and Dihalomethyllithiums

“…Moreover, discrete improvement of regiocontrol has been achieved through the formal geminal dihalogenation of β-oxo carboxylic derivatives (esters or acids). [12] Although effective and, in particular instances occurring with enantioinduction, [13] the requirement for the extra decarboxylation step renders the procedure not direct (Scheme 1 -path c). With the aim to improve the control of the halonium attack, putative α-oxocarbanions resulted as interesting and valuable solutions.…”

“…In this context, the Wu's modification [10] of Colby's protocol [11] paved on an initial nucleophilic substitution of an enolate on a trifluoromethyl ester of methylketones followed by halogenation constitutes a significant advancement allowing the preparation of variously functionalized fluoro‐haloketones (Scheme 1 – path b ). Moreover, discrete improvement of regiocontrol has been achieved through the formal geminal dihalogenation of β‐oxo carboxylic derivatives (esters or acids) [12] . Although effective and, in particular instances occurring with enantioinduction, [13] the requirement for the extra decarboxylation step renders the procedure not direct (Scheme 1 – path c ).…”