Thep alladium-catalyzed ketone-directed dual sp 2 C À Ha ctivation and sp 3 C À Hf unctionalization hasb een applied for fullerene functionalization for the first time.T he sec-alkyl aryl ketones have been exploited to react with [60]fullerene( C 60 )t o provide the novela nd scarce C 60 -fusedt etralones. Thec ombinedu se of ah ighly active cationicp alladium(II)c atalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. Ap lausible reactionm echanism leading to the observed products has been proposed, and the electrochemistry of the fullerene productsh as also been investigated.Keywords: C À Ha ctivation;f ullerenes;k etones; palladium Since the discovery of [60]fullerene (C 60 )i n1 985, its structure,p roperties andp otentiala pplications have attractede xtensive attention. Thes ynthesis of [60]fullerene derivatives possessingp romising functions in materials science and biomedicine is still highly desirable.N umerous methodologies for the chemical modification of fullerenes have been developed during the last two decades,i nvolving various cycloadditions,r adical additions,n ucleophilica dditions,a nd multiadditions.[1] However, the toolbox for fullerene functionalization remains comparatively limited. As one of the most efficientm ethodologies for the functionalization of fullerenes,m etal-catalyzed methodology offersm ore opportunities for creating novelf unctionalized fullerenes.[2] Recently,w es uccessfullyi ntroduced the palladium-catalyzed C À Ha ctivations trategyi nto fullerene chemistry,a nd synthesized as eries of novel[ 60]fullerene derivatives.[3] The C À Ha ctivation/C À Nc yclization strategy has been successfully applied to heteroannulations of C 60 with various anilides, [3a] N-benzylsulfonamides,[3b] N-sulfonyl-2-aminobiaryls, [4] and N-(2-arylethyl)sulfonamides,[3f] affording C 60 -fusedi ndolines, tetrahydroisoquinolines,i soquinolinones,a zepines,a nd tetrahydrobenzazepines,r espectively.T he C À Ha ctivation/C À Oc yclization strategyh as been successfully applied to heteroannulations of C 60 with various arylsulfonic acids [3c] andp henylethyl/benzyl alcohols, [3e] affording C 60 -fused sultones, tetrahydrobenzoxepines and isochromans,r espectively.H owever, an approach involving aC À Ha ctivation/C À Cc yclization strategyt of orm C 60 -fusedc arbocycles remains unexploited (Scheme 1).TheP d-catalyzed, ketone-directed C À Ha ctivation reactions are still scarce andc hallenging, since the ketonea sahard Lewis base and aw eak s donor generally does not coordinate strongly with the palladium catalyst, which leads to lowerr eactivity.U pto now, only af ew examples using ketones as ad irecting group for the Pd-catalyzed C À Ha ctivation reactions have been reported.[5] Recently,t he Cheng group reported an important discovery of Pd-catalyzed C À H activation/C À Cc oupling of sec-alkyl aryl ketones with aryl iodides.[5a] Subsequently,apractical Pd(II)-catalyzed ortho C À Ha midation of aromatic ketones was disclosedb yt he Liu group.[5b] La...

A convenient and facile palladium-catalyzed reaction of [60]fullerene (C60) with 2-aryl cyclic 1,3-dicarbonyl compounds via the enolate-directed sp(2) C-H activation and sp(3) C-H functionalization has been exploited to synthesize the novel and rare C60-fused spiroindanes for the first time. This reaction is easy to perform with broad substrate scope and provides diversified products in 20-50% yields. A plausible reaction mechanism involving the palladium-catalyzed enolate-directed C-H activation and subsequent cyclization has been proposed, and the electrochemistry of the C60-fused spiroindanes has also been investigated.

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