Access to α-Cyano Carbonyls Bearing a Quaternary Carbon Center by Reductive Cyanation
Xinyi Ren, Chaoren Shen, Guangzhu Wang, Zhanglin Shi, Xinxin Tian* and Kaiwu Dong*
*Shanxi University, Taiyuan 030006; East China Normal University, Shanghai 200062, P. R. China, Email: tianxxsxu.edu.cn, kwdongchem.ecnu.edu.cn
X. Ren, C. Shen, G. Wang, Z. Shi, X. Tian, K. Dong, Org. Lett., 2021, 23, 2527-2532.
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A reductive cyanation of tertiary alkyl bromides using an electrophilic cyanating reagent and zinc reductant provides various α-cyano ketones, esters, and carboxamides containing a nitrile-bearing all-carbon quaternary center in very good yields under mild reaction conditions.
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General Procedure for the synthesis of α-cyanoketones
To a 15 mL flame-dried reaction tube containing a magnetic stir bar was charged with α-bromoketone (0.50 mmol, 1.0 equiv.), cyanating reagent (163.2 mg, 0.6 mmol, 1.2 equiv.). The tube was evacuated and backfilled with N2 (×3), Zn dust (39.2 mg, 0.60 mmol, 1.2 equiv) and DMF (2.0 mL) were added in glovebox. The reaction tube was capped, removed from the glove box. The resulting mixture was allowed to stir at rt for 2 h. The residual mixture was diluted with water (10 mL), and extracted with ethyl acetate (3 × 10 mL). The combined organic phase was dried over NaSO4, filtered, and solvent was removed in vacuum. The residue was purified by flash column chromatography on silica gel, affording the corresponding α-cyanoketones.