Imidazolylzinc chloride

Many aryl- and heteroarylzinc reagents have been coupled with halopyridines. Examples include arylzincate 20 derived from ethyl benzoate [3], thienylzinc reagent 21 [16], 2-imidazolylzinc chloride 22 [17], pyrazolylzinc reagent 23 [18], and 2-pyridylzinc reagent 24 [19]. 

This method of imidazolylzinc chloride synthesis has also found application in the synthesis of a sulfonyl chloride to be used in the preparation of some potential factor Xa inhibitors [17]. Thus, following imidazole metalation and quenching with ZnCl2, a chemoselective coupling reaction occurred to provide 16. Treatment with sulfur dioxide provided the sulfinic acid, which upon treatment with thionyl chloride, provided the requisite sulfonyl chloride 17. 

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