An extraordinarily efficient hybrid acidsassisted, palladium-catalyzed and chelating-group-assisted C À H bond activation of N-sulfonyl-2-aminobiaryls and their annulations with [60]fullerene via sequential C À C and C À N bond formation at room temperature to afford [60]fulleroazepines is demonstrated. The formation of [60]fulleroazepines is highly regioselective and tolerant to both electronwithdrawing and electron-donating groups on the aryl moiety and the reaction gives monofunctionalized fullerenes in good yields (up to 54% isolated yield and 92% based on converted C 60 ).
We report herein a convenient route to the synthesis of aryl‐substituted γ‐lactones bearing an α‐phosphorus ylide moiety through the assembly of dimethyl acetylenedicarboxylate (DMAD), electron‐deficient aldehydes, and triaryl‐ or trialkylphosphanes in moderate to good yields. The formation of γ‐lactones is highly dependent on the reaction time, the phosphane nucleophile, and the molar ratio of DMAD, aldehyde, and phosphane. We found that reactions with a DMAD/aldehyde/tri‐p‐tolylphosphane molar ratio of 3:1:6 and more electron‐deficient aldehydes, such as 4‐nitrobenzaldehyde and 4‐chloro‐3‐nitrobenzaldehyde, gave good yields. The isolated ylides reacted with aldehydes as Wittig reagents to give olefins in moderate yields.
Organophosphanes promote the [3+2] cycloaddition reactions of dialkyl (E)‐hex‐2‐en‐4‐ynedioates and [60]fullerene, giving a series of cyclopenteno‐fullerenes 3a–k bearing phosphorus ylides. This cycloaddition reaction is initiated by the attack of nucleophilic phosphanes at the α(δ′)‐C atom of the dialkyl (E)‐hex‐2‐en‐4‐ynedioate, which generates a 1,3‐dipolar species. These 1,3‐dipoles then react with C60 followed by intramolecular cyclization to give cyclopenteno‐fullerenes in moderate‐to‐good yields. In a cyclic voltmmetry study, these novel fullerenes show a larger cathodic shift in their first reduction potential relative to [6,6]phenyl‐C61 methyl butyrate, which indicates that these new derivatives possess higher LUMO energy levels.
An efficient palladium-catalyzed addition reaction of alkyl- and arylsulfonic acids to propiolate esters to yield alkenyl sulfonates is demonstrated. The formation of alkenyl sulfonates is highly regio- and stereoselective with favorable yields of up to 95%, and two of the alkenyl sulfonates are utilized for a Sonogashira cross-coupling reaction to produce (Z)-1,3-enynoates.
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