Tris(cyclopentadienyl)lanthanide Complexes as Catalysts for Hydroboration Reaction toward Aldehydes and Ketones
Sufang Chen, Dandan Yan, Mingqiang Xue*, Yubiao Hong, Yingming Yao* and Qi Shen*
*College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China, Email: xuemingqiangsuda.edu.cn, yaoymsuda.edu.cn, qshensuda.edu.cn
S. Chen, D. Yan, M. Xue, Y. Hong, Y. Yao, Q. Shen, Org. Lett., 2017, 19, 3382-3385.
Homoleptic cyclopentadienyl lanthanide complexes are excellent catalysts for the hydroboration of various aldehydes and ketones with pinacolborane. These robust lanthanide catalysts exhibited high reactivity with low catalyst loadings under mild conditions, good functional group tolerability, and unique carbonyl-selectivity.
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Hydrolysis: The hydroborated product was exposed to air, a spoon of silica gel was then added, and refluxed with CHCl3 (3 mL) and H2O (3 mL) for 24 h. The reaction mixture was diluted with water (6 mL) and extracted with CHCl3 (6 mL × 3 times). The organic phases were combined, evaporated and purified by column chromatography over silica-gel (100-200 mesh) using ethyl acetate/hexane (1:10 or 1:20) mixture as eluent. The resulting alcohol was characterized by 1H and 13C NMR.
Mingqiang Xue, April 10, 2018