N-Hydroxyphthalimide Derivatives for the Synthesis of Redox Active Esters

4-methyl-N-hydroxyphthalimide (1) and 4-methoxy-N-hydroxyphthalimide (2) condense with aliphatic carboxylic acids to produce redox active esters (RAEs). RAEs can generate equivalent alkyl radicals by single electron reduction and can be applied to C(sp²)-C(sp³) cross-coupling reactions with aryl bromides and aryl iodides.¹⁾ In conventional RAE synthesis, N-hydroxyphthalimide (3) has been widely used. However, RAEs derived from 3 are more easily reduced, so that the density of alkyl radical becomes excess to lead side reactions such as dimerization. On the other hand, it has been reported that RAEs derived from 1 and 2 are more electron-rich, resulting in lower reduction potential and suppression of side reactions. Therefore, 1 and 2 are effective when carboxylic acids with tertiary alkyl group known as a bioisostere of benzene and less reactive aryl bromides are used. Furthermore, it has been reported that RAEs obtained from 1 can be used for C(sp³)-C(sp³) cross-coupling reactions with inert alkyl bromides.²⁾

Related Products

M3571

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4,4'-Di-tert-Butyl-N-cyano[2,2'-bipyridine]-6-carboximidamide (= ^tBuBpyCam^CN)

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References

• 1) Control of Redox-Active Ester Reactivity Enables a General Cross-Electrophile Approach to Access Arylated Strained Rings
  • D.C. Salgueiro, B. K. Chi, I. A. Guzei, P. García-Reynaga, D. J. Weix, Angew. Chem. Int. Ed. 2022, 61, e202205673.
• 2) Nickel-Catalyzed C(sp³)–C(sp³) Cross-Electrophile Coupling of In Situ Generated NHP Esters with Unactivated Alkyl Bromides
  • K. Kang, D. J. Weix, Org. Lett. 2022, 24, 2853.

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