On the Regioselective Intramolecular Nucleophilic Addition of Thiols to C₆₀

Abstract

The first intramolecular nucleophilic addition of a thiol to a fullerene double bond is reported. Whereas the reaction of cysteine (4) or cystine (11) with formaldehyde and [60]fullerene in chlorobenzene at reflux afforded the new compound 10 bearing a thiazolidine moiety fused to the fullerene sphere, the reaction of commercially available N-methylglycine (12; sarcosine) with 1,4-dithiane-2,5-diol (13) and C 60 in chlorobenzene at reflux led to the desired cyclized compound 3 in poor yield. The favorable geometrical approach of the reactive thiol group towards the fullerene double bond is followed by a 5-exo-trig intramolecular nucleophilic addition of the S-H group to the adjacent double bond of the fullerene to form compound 3 in which a tetrahydrothiophene ring is simultaneously fused to the pyrrolidine and the fullerene moieties. Compound 3 was spectroscopically and electrochemically characterized and CV revealed that saturation of a second double bond of the fullerene sphere (cis-1 regioisomer) is compensated by the electronegative charac-

Unexpected Isomerism in cis‐2 Bis(pyrrolidino)[60]Fullerene Diastereomers

“…[10] This method was used to conduct bis(1,3-dipolar cycloaddition)s to C 60 by DSouza et al and Zhou et al [11,12] Examples of regioselective syntheses of bis(adduct)s with a cis-1 addition pattern were reported by Martín et al, who used an intramolecular Pauson-Khand reaction, thermal [2+2] cycloaddition, [13] and nucleophilic addition. [14] Also, selective tether-controlled tandem additions of nitrile oxides and azomethine ylides to yield cis-1 bis(adduct)s were reported by Prato et al [15] Herein we report the one-step synthesis and characterization of three pure [60]fullerene bis(adduct)s, including the X-ray crystal structure of two cis-2 bisadducts (1 and 2; see Scheme 1 for structures) which are individual meso forms. Although there are multiple reports of chirality for fullerene derivatives, [16,4] the isomerism reported here is unprecedented.…”

Applications and validations of the Minnesota density functionals

“…Based on these benchmarking results, Izquierdo et al [61] employed the recommended methods to study regioselective intramolecular nucleophilic addition of alcohols to C 60 , which provides one-step formation of a bicyclic-fused fullerene with an oxygen-containing five-member ring.…”

Synthesis and properties of bis(pyrrolidino)fullerenes bridged by a flexible alkyl-tether

“…It should be mentioned that bisadducts were also obtained by regioselctive intramolecular reactions involving [2þ2]-cycloaddition 24 and nucleophilic addition. 25 Increasing functionalization of the fullerene reduces the aggregation of obtained derivatives and consequently improves their solubility, expanding at the same time the possibility of application. Therefore we supposed that formation of bis(pyrrolidino)fullerenes, bridged by a flexible alkyl chain could contribute to the study of the bisaddition selectivity, as well as to the development of upgraded, more soluble fullerene derivatives.…”