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DOI: 10.1055/sos-SD-207-00504

Undheim, K.Science of Synthesis: Cross Coupling and Heck-Type Reactions, (20131761.

Hetaryl compounds are also useful for constructing ketones from carbonyl chlorides (Scheme 37). The hetarylzinc reagents undergo coupling reactions with the highly electrophilic acid chlorides. However, this type of C—C bond formation is not discussed in detail in this report. In Scheme 37, the cross coupling is illustrated by the reaction between 2-pyridylzinc bromide (14) and 2-chloronicotinoyl chloride (120). The chlorine of the acid chloride functional group is more reactive. Cross coupling proceeds with no added catalyst.[‌50‌] In most cases, ketone formation is commonly promoted by initial transmetalation of the hetarylzinc reagent to a hetarylcopper reagent.[‌51‌] The cupration is readily induced by the soluble copper(I) cyanide–bis(lithium chloride) complex (CuCN•2LiCl). In Scheme 37, the nucleophile is formed by direct oxidative zincation of 2,5-dichloropyrazine 121. The hetarylzinc reagent 122 is subsequently transmetalated to give a hetarylcopper complex, which then reacts with the electrophilic benzoyl chloride to form ketone 123.[‌51‌]

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