Notably Enhanced Reactivity of the Fulleroid anti‐Bredt Double Bond in Diels–Alder Reactions

Abstract

(3d) and 2-methylbutadiene (3e)] has been carried out in toluene at 30°C. Notably, the relative rate ratio k/k 0 for each dienophile (vs. C 60 ) was remarkably dependent on the diene used; the less hindered H/CN fulleroids 1a and 1b became 25-104 times more reactive than C 60 with conformationally flexible dienes such as 3d and 3e. These fulleroids, however, showed similar or rather diminished reactivity with rigid 3a and 3b. In contrast,

Fullerenes

“…The relative reactivity of the fulleroids vs. C 60 was found to be dependent on the identity of the diene as well as the fulleroid substituent. 30 Pyridyl and phenyl-containing dihydrofuranfused C 60 derivatives were prepared by the base-catalysed or Mn(OAc) 3 -mediated [3+2] cycloaddition reactions of C 60 with the corresponding b-keto esters in high yields. All the new compounds were characterised by elemental analysis and various spectroscopic methods.…”

“…133 A mixed-valence cluster of cobalt (11) hexacyanoferrate and fullerene C 60 -enzyme-based electrochemical glucose sensor was developed. 134 The preparation and spectroscopic characterisation of the water soluble sodium fullerenolate Na 4 [C 60 (OH) 30 ] has been reported. It has been revealed for the first time that sodium fullerenolate destroys amyloid fibrils of the Ab(1-42) peptide in the brain and prevents their formation in in vitro experiments.…”

A theoretical study for the regioselective Diels–Alder reaction of 5,6‐fulleroid with strained anti‐Bredt olefins

“…Fulleroid and azafulleroid have reactive anti‐Bredt olefins at the bridgehead position (Scheme B). The high regioselectivity of them has been reported in hydrogenation, oxidation with singlet oxygen and peracid, Diels–Alder reaction, and 1,3‐dipolar cycloaddition …”

“…Material application of the difunctionalized fullerene via the 5,6‐monoadduct has not been well explored except for bisazafulleroid because its regioselectivity depends on the reactants and substituents of fulleroid. For the evaluation of the regioselectivity of 5,6‐bridged monoadduct, our research group previously reported that the reactivity and regioselectivity of Diels–Alder reaction of variously substituted fulleroids with noncyclic and cyclic dienes . Flexible noncyclic dienes such as 2,3‐dimethyl‐1,3‐butadiene (DMBD) showed higher kinetic constants than that of C 60 with high regioselectivity on the bridgehead olefins.…”

“…At first, the orbital distribution and intrinsic olefin strain of anti‐Bredt and the other olefins are evaluated. Second, transition state (TS) calculations are carried out for the reaction with noncyclic diene DMBD in comparison with the experimental results . Its reactivity is compared with pristine C 60 and methanofullerene, the 6,6‐bridged regioisomer of fulleroid.…”