Annulation of Benzamides with [60]Fullerene through Palladium(II)-Catalyzed C−H Bond Activation

Abstract

Palladium-catalyzed heteroannulation of N-substituted benzamides with [60]fullerene, which proceeds through direct sp(2) C-H bond activation to form 7-membered ring pallada-intermediate with C(60), led to formation of [60]fulleroisoquinolinones in moderate to good yields (8-64% based on recovered C(60)). A plausible reaction pathway is proposed.

Palladium‐Catalyzed and Hybrid Acids‐Assisted Synthesis of [60]Fulleroazepines in One Pot under Mild Conditions: Annulation of N‐Sulfonyl‐2‐aminobiaryls with [60]Fullerene through Sequential C‐H Bond Activation, C‐C and C‐N Bond Formation

“…of pTsOH in 6.2 mL of ODCB/TFA (6:0.2) at ambient temperature, the desired monofunctionalized fullerene product 2a was isolated in good chemical yield (37%; 48% based on converted C 60 , entry 9). K 2 S 2 O 8 was also an effective oxidant for this functionalization when compared to other metal oxidizing agents (entry 10 vs. entries [4][5][6][7][8]. We noted that increasing reaction temperature or time did not improve reaction yields (entries [11][12][13][14][15].…”

“…The reaction conditions were optimized with N-tosyl-2-aminobiphenyl (1a) as a model substrate and the results are summarized in Table 1. Initially, we attempted the present reaction with our previously reported conditions [4] using CuA C H T U N G T R E N N U N G (OAc) 2 as an oxidant in o-dichlorobenzene (ODCB)/trifluoroacetic acid (TFA) solvent (6:1) at 120 8C; unfortunately, no desired product 2a was observed (Table 1, entry 1). Neither was 2a observed without TFA in control experiments (entries 2 and 3).…”

“…In this context, palladium-mediated reactions of small molecules with fullerenes have been relatively more explored. [3a-e] With the greener C À H bond activation methodology, we recently have achieved the annulation of benzamides with [60]fullerene through palladium(II)-catalyzed C À H bond activation and prepared fulleroisoquinolinones [4] for their applications as n-type materials in highly-efficient organic photovoltaics (OPVs).…”

Amide‐Directed Tandem CC/CN Bond Formation through CH Activation

“…, top) 46. Chuang, Wang, and co‐workers reported the palladium‐catalyzed synthesis of fulleroisoquinolinones by the annulation of C 60 with N ‐alkyl benzamides through CH activation (Scheme , bottom) 47. Trifluoroacetic acid was used as a key co‐solvent for improving the reaction performance.…”

Evolution of Late Transition‐Metal‐Catalyzed Intermolecular Reductive Coupling Reaction of [60]Fullerene and N‐Sulfonylaldimines: Competing Formation of Hydrobenzylated [60]Fullerenes and 1,2‐Dihydrofullerene

“…Previous studies have recognized that some transition metals, such as palladium,3a–3e rhodium,3f–3j cobalt,3k–3m manganese,3n–3q iron,3r,3s and copper,3t–3v can mediate functionalization of the fullerene sphere. In this context, we have recently also reported annulations of benzamides with [60]fullerene through palladium(II)‐catalyzed C–H bond activation4 to afford fullero‐isoquinolinones. In 1998, Cheng et al first reported a nickel‐catalyzed [2+2+2] cycloaddition between C 60 and a tethered diyne mediated by stoichiometric amounts of nickel complexes;5 this study is to date the only example of [60]fullerene functionalization mediated by nickel complexes.…”