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Ir-Catalyzed Chemoselective Reductive Condensation Reactions of Tertiary Amides with Active Methylene Compounds

Dong-Ping Wu, Wei Ou and Pei-Qiang Huang*

*Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, P. R. China, Email: pqhuangxmu.edu.cn

D.-P. Wu, W. Ou, P.-Q. Huang, Org. Lett., 2022, 24, 5366-5371.

DOI: 10.1021/acs.orglett.2c02045


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Abstract

Iridium-catalyzed hydrosilylation of tertiary amides followed by acid-mediated condensation with active methylene compounds provides multifunctionalized non-N-containing products. This scalable method is broad in scope and shows remarkable chemoselectivity for the amide group in the presence of functionalities such as ester, cyano, nitro, silyl dienol ether, and ketone.

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proposed mechanism



General Procedure for the Reductive Olefination of tert-Amides

To a solution of an amide (1.0 mmol) in anhydrous toluene (5.0 mL) was added Vaska's complex (0.2 mol%). The suspension was stirred for 5 minutes at room temperature. To the resulting yellow solution, TMDS (tetramethyldisiloxane, 1.4 mmol) was added in one portion and the reaction mixture stirred for 10 minutes until H2 gas evolution had ceased and the solution turned colorless. Then dimethyl malonate (1.8 mmol) was added in one portion and the mixture was stirred for 5 minutes. Finally, AcOH (1.2 mmol) was added in one portion and the mixture was stirred for 3 h at room temperature. The reaction was quenched with saturated aqueous NH4Cl solution and extracted with EtOAc (3 5 mL). The combined organic layers were washed with brine, dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by flash column chromatography to give the desired product.


Key Words

condensations with active methylenes, TMDS


ID: J54-Y2022