Cu(I)-Catalyzed Synthesis of [60]Fullerene-Fused Lactams and Further Electrochemical Functionalization

Abstract

A novel and efficient Cu­(I)-catalyzed radical heteroannulation reaction of [60]­fullerene (C60) with α-bromo acetamides has been disclosed for the direct synthesis of diverse C60-fused lactams. Furthermore, the formed C60-fused lactams can be served as a versatile platform for further electrochemical functionalization to prepare 1,2-, 1,4-, 1,2,3,16-, and 1,4,9,25-adducts of C60. In addition, a representative fullerene product has been applied as an overcoating layer of the electron-transporting layer in n-type perovskite solar cell.

Electrochemically Promoted Benzylation of [60]Fullerooxazolidinone

“…The UV-vis spectrum of 3 exhibited two strong absorption bands at 254 and 324 nm, together with three weak absorption bands at 405, 431 and 690 nm, which were similar to those of 1,2,3,16-adducts in the literature [26,27,[30][31][32][33]35,37,38]. However, in the UV-vis spectrum of product 4, three strong absorption bands at 250, 268 and 330 nm, together with five weak absorption bands at 409, 450, 510, 591 and 672 nm were observed, and were very similar to those of 1,4,9,25-adducts in the literature [32,35].…”

“…The 13 C NMR spectrum of 2 showed 50 peaks for the 58 sp 2 -carbon atoms in the 156.15-137.93 ppm range and two sp 3 -carbon atom peaks of the fullerene cage at 68.28 and 60.01 ppm, and the 13 C NMR spectra of 3 and 4 displayed at least 52 peaks between 156.04-135.95 ppm for the 56 sp 2 -carbon atoms and four peaks between 90.31-56.52 ppm for the four sp 3 -carbon atoms of the fullerene skeleton, agreeing with their C 1 symmetry. The UV-vis spectrum of 2 showed a broad absorption band at 446 nm, which resembled those of other 1,4-adducts of C 60 [35,40,41]. The UV-vis spectrum of 3 exhibited two strong absorption bands at 254 and 324 nm, together with three weak absorption bands at 405, 431 and 690 nm, which were similar to those of 1,2,3,16-adducts in the literature [26,27,[30][31][32][33]35,37,38].…”

“…On balance, we carried out our experiments on 1 (0.01 mmol) at a lower temperature of 15 • C. By controlled potential electrolysis (CPE) of 1 at −1.09 V in 1,2-C 6 H 4 Cl 2 solution containing 0.1 M tetra-n-butylammonium perchlorate (TBAP) at 15 • C under an atmosphere of argon, dianion 1 2− was generated after acceptance of two electrons. Similar to other dianionic C 60 -fused heterocycles, the ring-opened singly-bonded fullerenyl dianion was attained after addition of two electrons [26][27][28][29][30][31][32][33][34][35][36][37], as confirmed by the very different CV of dianion 1 2− (Figure S21) compared to that of neutral 1 (Figure 1). Then, 1 2− was treated with 20 equiv.…”

“…All of these reactions involved the rearrangement of the indoline moiety from a [6,6]-bond to a [5,6]-bond. Similar electrosynthesis involving rearrangements of heterocyclic moieties on the fullerene surface for other C 60 -fused heterocycles resulted in 1,2,3,4-, 1,2,3,16-and 1,4,9,25-adducts [31][32][33][34][35]. The electrochemical reactions of heterocyclic fullerene derivatives fused with two heteroatoms have also been reported.…”

Copper‐Promoted Cascade Radical Reaction of [60]Fullerene with Arylglyoxals and Further Derivatization

“…In an n‐type perovskite solar cell (PSC), fullerene derivatives could improve the power conversion efficiency (PCE) whereas C 60 showed no effective passivation as an overcoating layer to modify the SnO 2 electron‐transporting layer (ETL) [10o,p,21] . As a proof, our synthesized representative product 2 a and its derivatives 3 a , 3 a′ , 4 a and 4 a′ were applied in PSCs as an overcoating layer with the configuration of ITO/SnO 2 /Fullerene/MAPbI 3 /Spiro‐OMeTAD/Ag (Figure 1a).…”