Palladium-catalysed heteroannulation of [60]fullerene with N-benzyl sulfonamides and subsequent functionalisation

Abstract

The palladium-catalysed heteroannulation of [60]fullerene with various N-benzyl sulfonamides via C-H bond activation affords [60]fullerene-fused tetrahydroisoquinolines. In the presence of a Brønsted acid [60]fullerene-fused tetrahydroisoquinolines are transformed to [60]fullerene-fused indanes, in which the sulfonamide group can be removed or replaced with an aryl group.

Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 CH Activation and sp3 CH Functionalization

“…As shown in Table 2, the isolated yields of 2a – l were 10–31% (31–72% based on consumed C 60 ). These yields are comparable to those reported for other monoadducts of C 60 , e.g., 18–30% yields for C 60 ‐fused sultones,3c 17–33% yields for C 60 ‐fused tetrahydroisoquinolines,3d 11–32% yields for C 60 ‐fused sulfamides,9a and 17–35% yields for C 60 ‐fused pyrrolines 9b…”

“…Recently, we successfully introduced the palladium‐catalyzed CH activation strategy into fullerene chemistry, and synthesized a series of novel [60]fullerene derivatives 3. The CH activation/CN cyclization strategy has been successfully applied to heteroannulations of C 60 with various anilides,3a N ‐benzylsulfonamides,3d N ‐substituted benzamides,3b N ‐sulfonyl‐2‐aminobiaryls,4 and N ‐(2‐arylethyl)sulfonamides,3f affording C 60 ‐fused indolines, tetrahydroisoquinolines, isoquinolinones, azepines, and tetrahydrobenzazepines, respectively. The CH activation/CO cyclization strategy has been successfully applied to heteroannulations of C 60 with various arylsulfonic acids3c and phenylethyl/benzyl alcohols,3e affording C 60 ‐fused sultones, tetrahydrobenzoxepines and isochromans, respectively.…”

Fullerenes

“…An effective way for the synthesis of C 60 -fused tetrahydroisoquinolines via Pd-catalysed heteroannulation of C 60 with N-benzyl sulfonamides via C-H bond activation has been discovered. 64 Direct thermal reaction of C 60 with amino acids or amino acid esters in refluxing o-dichlorobenzene and in the absence of aldehydes under aerobic and dark conditions has been investigated. 65 Four novel C 60 -pyrrolidines containing trifluoromethyl group have been synthesised via 1,3-dipolar cycloaddition reactions and have been characterised by various spectroscopic techniques.…”

FeCl3-Mediated Cyclization of [60]Fullerene with N-Benzhydryl Sulfonamides under High-Speed Vibration Milling Conditions

“…For example, the product yield of 2g was decreased from 41% (64% based on consumed C 60 ) with 14.4 mg of C 60 for 1 h to 28% (51% based on consumed C 60 ) with 50.0 mg of C 60 for 2 h. The chloro and bromo groups in products 2d – g (Table , entries 4–8) may be used as a handle for further coupling reactions. The methods for the synthesis of fulleroindanes are still limited. ,, The synthesis of fulleroindane 2a was previously reported by us and required three steps starting from C 60 . Obviously, the present mechanochemical protocol in only one step is much more concise and efficient.…”