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Synthesis of 2‐ and 2,7‐Functionalized Pyrene Derivatives: An Application of Selective CH Borylation
Author(s) -
Crawford Andrew G.,
Liu Zhiqiang,
Mkhalid Ibraheem A. I.,
Thibault MarieHélène,
Schwarz Nicolle,
Alcaraz Gilles,
Steffen Andreas,
Collings Jonathan C.,
Batsanov Andrei S.,
Howard Judith A. K.,
Marder Todd B.
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201103774
Subject(s) - borylation , chemistry , pyrene , nucleophile , electrophile , medicinal chemistry , stereochemistry , negishi coupling , organic chemistry , catalysis , aryl , alkyl
An efficient synthetic route to 2‐ and 2,7‐substituted pyrenes is described. The regiospecific direct CH borylation of pyrene with an iridium‐based catalyst, prepared in situ by the reaction of [{Ir(μ‐OMe)cod} 2 ] (cod=1,5‐cyclooctadiene) with 4,4′‐di‐ tert ‐butyl‐2,2′‐bipyridine, gives 2,7‐bis(Bpin)pyrene ( 1 ) and 2‐(Bpin)pyrene ( 2 , pin=OCMe 2 CMe 2 O). From 1 , by simple derivatization strategies, we synthesized 2,7‐bis(R)‐pyrenes with R=BF 3 K ( 3 ), Br ( 4 ), OH ( 5 ), B(OH) 2 ( 6 ), and OTf ( 7 ). Using these nominally nucleophilic and electrophilic derivatives as coupling partners in Suzuki–Miyaura, Sonogashira, and Buchwald–Hartwig cross‐coupling reactions, we obtained 2,7‐bis(R)‐pyrenes with R=(4‐CO 2 C 8 H 17 )C 6 H 4 ( 8 ), Ph ( 9 ), C≡CPh ( 10 ), C≡C[{4‐B(Mes) 2 }C 6 H 4 ] ( 11 ), C≡CTMS ( 12 ), C≡C[(4‐NMe 2 )C 6 H 4 ] ( 14 ), C≡CH ( 15 ), N(Ph)[(4‐OMe)C 6 H 4 ] ( 16 ), and R=OTf, R′=C≡CTMS ( 13 ). Lithiation of 4 , followed by reaction with CO 2 , yielded pyrene‐2,7‐dicarboxylic acid ( 17 ), whilst borylation of 2‐ t Bu‐pyrene gave 2‐ t Bu‐7‐Bpin‐pyrene ( 18 ) selectively. By similar routes (including Negishi cross‐coupling reactions), monosubstituted 2‐R‐pyrenes with R=BF 3 K ( 19 ), Br ( 20 ), OH ( 21 ), B(OH) 2 ( 22 ), [4‐B(Mes) 2 ]C 6 H 4 ( 23 ), B(Mes) 2 ( 24 ), OTf ( 25 ), C≡CPh ( 26 ), C≡CTMS ( 27 ), (4‐CO 2 Me)C 6 H 4 ( 28 ), C≡CH ( 29 ), C 3 H 6 CO 2 Me ( 30 ), OC 3 H 6 CO 2 Me ( 31 ), C 3 H 6 CO 2 H ( 32 ), OC 3 H 6 CO 2 H ( 33 ), and O(CH 2 ) 12 Br ( 34 ) were obtained from 2 . These derivatives are of synthetic and photophysical interest because they contain donor, acceptor, and conjugated substituents. The crystal structures of compounds 4 , 5 , 7 , 12 , 18 , 19 , 21 , 23 , 26 , and 28 – 31 have also been obtained from single‐crystal X‐ray diffraction data, revealing a diversity of packing modes, which are described in the Supporting Information. A detailed discussion of the structures of 1 and 2 , their polymorphs, solvates, and co‐crystals is reported separately.