Selective synthesis of α-chloroepoxides by electroreductive cross-coupling of methyl trichloroacetate with aliphatic aldehydes using reactive metal anodes

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…715 In another variant, the electrochemical reduction of trichloroacetates was applied to synthesize α -chloroepoxides (Figure 42J, bottom). 716 In this case, the gem -dichlorocarbanions generated by direct cathodic reduction of C–Cl bond can undergo a Darzens reaction to give α -chloroepoxides. Chelation of Zn(II) ion in the transition state presumably allowed for high stereoselectivity.…”

“…Similar processes were exploited in the preparation of 4-amino-2-aryl-2-oxazolines, quinolinones, and coumarins . In another variant, the electrochemical reduction of trichloroacetates was applied to synthesize α-chloroepoxides (Figure J, bottom) . In this case, the gem -dichlorocarbanions generated by direct cathodic reduction of C–Cl bond can undergo a Darzens reaction to give α-chloroepoxides.…”

Use of Electrochemistry in the Synthesis of Heterocyclic Structures

“…Electrogenerated gem -dichloro carbanions from electrochemical reduction of trichloroacetate can undergo electrophilic attack of some reagents, such as proton, α,β-unsaturated compounds, and carbonyl compounds. , Nishiguchi et al reported a stereoselective and facile synthesis of 2-chloroepoxyester 412 through electroreductive cross-coupling of methyl trichloroacetate 411 with aliphatic aldehydes (Scheme ). With tetraethylammonium p -toluenesulfonate (Et 4 NOTs) in DMF as supporting electrolyte, constant current electrolysis of 411 with aldehydes in the presence of trimethylsilyl chloride was performed in an undivided cell equipped with a Zn rod as the sacrificial anode and cathode. It was observed that sec - or tert -aliphatic aldehydes gave good yields of corresponding α-chloroepoxyesters, whereas complex mixture was obtained from reaction with primary aliphatic aldehydes.…”