Selective Synthesis of (Z)- and (E)-β-Fluoro-α,β-Unsaturated Amides Using Palladium-Catalyzed Aminocarbonylation
Su Hyeon Park and Sunwoo Lee*
*Department of Chemistry, Chonnam National University,
Gwangju 61186, Republic of Korea, Email: sunwoo
chonnam.ac.kr
S. H. Park, S. Lee, Org. Lett., 2023, 25, 6925-6930.
DOI: 10.1021/acs.orglett.3c02809
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Abstract
Palladium-catalyzed aminocarbonylations of 1-fluoro-2,2-diiodovinylarenes provide (Z)- and (E)-β-fluoro-α,β-unsaturated amides. Using {Pd(allyl)Cl}2 as a catalyst and DBU as a base in DMF, the primary product is the (Z)-isomer. Conversely, the use of a Xantphos ligand along with {Pd(allyl)Cl}2 and Et3N as the base in 1,4-dioxane leads to the selective formation of the (E)-isomer.
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proposed mechanisms
General procedure for the synthesis of (Z)-β-fluoro-α,β-unsaturated amides from various 1-fluoro-2,2-diiodovinyl arenes
To a 20 mL vial was charged with 1-fluoro-2,2-diiodovinylarene (1.0 mmol), amine (1.2 mmol), [Pd(allyl)Cl]2 (9.1 mg, 0.025mmol) and DBU (304.5 mg, 2.0 mmol) were added to DMF (5.0 mL) in the autoclave. The autoclave was closed, purged with carbon monoxide, pressurized with 5.0 atm, and then stirred at 80 °C for 5 h. Excess carbon monoxide was discharged at room temperature. The reaction was diluted with ethyl acetate. The organic layer was washed with water, dried with MgSO4, filtered, and concentrated under vacuum. The crude product was purified by silica gel column chromatography with ethyl acetate/hexane to afford the product.
Key Words
aminocarbonylation, fluoroalkenes, alkenylation
ID: J54-Y2023
