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Regioselective Synthesis of [6,6]‐Open and [5,6]‐Closed C 70 (CF 3 ) 8 [CH 2 ] Methanofullerenes with Rapid [6,6]‐to‐[5,6] Phototransformation
Author(s) -
Semivrazhskaya Olesya O.,
Belov Nikita M.,
Rybalchenko Alexey V.,
Markov Vitaliy Yu.,
Ioffe Ilya N.,
Lukonitalia S.,
Troyanov Sergey I.,
Kemnitz Erhard,
Goryunkov Alexey A.
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201701610
Subject(s) - chemistry , diazomethane , regioselectivity , fullerene , bond cleavage , photodissociation , thermal decomposition , cycloaddition , pyrazoline , double bond , single bond , stereochemistry , photochemistry , medicinal chemistry , catalysis , organic chemistry , alkyl
Fullerene derivatives with >CH 2 addends in [6,6]‐open or [5,6]‐closed configuration are uncommon of fullerene derivatives, but they are readily accessible via treatment of C s ‐C 70 (CF 3 ) 8 with diazomethane followed by thermolysis or photolysis. Both thermodynamic and kinetic factors favor regioselective addition of diazomethane at the near‐equatorial [5,6]‐double bond of C s ‐C 70 (CF 3 ) 8 to give a thermally labile pyrazoline intermediate. Thermal extrusion of N 2 from the latter is a kinetically controlled process with orbital symmetry controlled Woodward–Hoffmann‐allowed mechanism. It quantitatively yields the less thermodynamically favorable [6,6]‐open isomer of C 70 (CF 3 ) 8 [CH 2 ] homofullerene, but the latter turns out to be capable of unexpectedly rapid quantitative phototransformation into the thermodynamically preferable [5,6]‐closed methanofullerene isomer. The transformation involves the manifold of the triplet states that facilitate the required cleavage of the C cage –CH 2 bonds.