Nickel-Catalyzed Arylation of C(sp³)-O Bonds in Allylic Alkyl Ethers with Organoboron Compounds

Xiaowei Li, Yuxiu Li, Zhong Zhang, Xiaolin Shi, Ruihua Liu, Zemin Wang, Xiangqian Li and Dayong Shi*

*State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, Qingdao 266237, P. R. China, Email: shidayongsdu.edu.cn

X. Li, Y. Li, Z. Zhang, X. Shi, R. Liu, Z. Wang, X. Li, D. Shi, Org. Lett., 2021, 23, 6612-6616.

DOI: 10.1021/acs.orglett.1c01879

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Abstract

A nickel-catalyzed cross-coupling of allylic alkyl ethers with organoboron compounds provides the corresponding products in very good yields via the cleavage of the inert C(sp³)-O(alkyl) bonds with wide functional group tolerance and excellent regioselectivity. A gram-scale reaction and late-stage modification of biologically active compounds further prove the practicality of this method.

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mechanistic study and proposed mechanism

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General procedure for Ni-catalyzed cross-coupling reaction

To a 10 mL Schlenk tube equipped with a magnetic stir bar was added allylic alkyl ether (0.1 mmol), organoboron compound (0.2 mmol, 2.0 equiv), PPh₃ (5.2 mg, 0.02 mmol, 20 mol%), and NaOAc (16.4 mg, 0.2 mmol, 2.0 equiv). Then, the reaction tube was taken to the argon-filled glove box, and Ni(cod)₂ (2.8 mg, 0.01 mmol, 10 mol%) and dry toluene (1 mL) were added. The resulting mixture was allowed to heat at 100 °C using oil bath for 12 hours under Ar until the reaction was complete (monitored by TLC). Concentration under reduced pressure gave a residue, which was purified by column chromatography on silica gel to give the corresponding product.

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Key Words

allylation, α,β-unsaturated compounds

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ID: J54-Y2021