δ-valerolactam derivative of C60 from hetero Diels-Alder reaction with 1,3-bis(tert-butyldimethylsiyloxy)-2-aza-1,3-butadiene

Fullerenes: functionalisation and prospects for the use of derivatives

“…1,3-Bis(tert-butyldimethylsilyloxy)-2-azabuta-1,3-diene (15) adds to C 60 fullerene at room temperature. 62 Hydrolysis, replacement of the silyloxy group by an alkoxy group (in order to avoid the retro-reaction) and dealkoxylation yield a fullerene derivative of d-valerolactam 16, which is a very interesting starting compound for the synthesis of amino acids and polyamides containing a fullerene fragment. These derivatives can be prepared after opening the six-membered ring.…”

Synthesis of Fullerotetrahydroquinolines by Cycloaddition Reaction of C60 with Aza-ortho-xylylenes

“…Furthermore, the methylene protons of an ethoxycarbonyl group appeared in a complex coupling pattern (d 4.33 and 4.47, each 1 H, dq, J=10.5 and 7 Hz) due to diastereotopic non-equivalency. The lack of C s -symmetry and the diastereotopic nature can be ascribed to sp 3 -configuration and no free inversion of a nitrogen atom involved in the tetrahydroquinoline ring. When this is the case, both methylene protons become no longer equivalent irrespective of free ring-flipping.…”

“…1,2 On the other hand, six-membered fulleroheterocycles have been so far achieved by hetero Diels-Alder reaction; for example, 2-aza-1,3-diene was applied for synthesis of d-lactam-fused C 60 . 3 In relevance to the reasonable use of o-quinodimethane to prepare a cycloirreversible cycloadduct in fullerene chemistry, 4 its oxa and thia heterologs were demonstrated to give fullerochroman and -thiochroman derivatives (Scheme 1: X=O, S). 5 In this series, we now wish to report a successful aza version (Scheme 1: X=NR) by using in situ generated aza-ortho-xylylenes with electron-withdrawing and electron-donating substituents and even no substituent on an imino group.…”

Cycloadditions

“…A few examples of hetero-Diels-Alder adducts have been reported [75][76][77][78][79][80][81]. A thiochroman-fused fullerene adduct was synthesized by the reaction of o-thioquinone with C 60 in o-dichlorobenzene at 180 °C [77].…”