Synthesis of 2‐ and 2,7‐Functionalized Pyrene Derivatives: An Application of Selective CH Borylation

Abstract

An efficient synthetic route to 2- and 2,7-substituted pyrenes is described. The regiospecific direct C-H 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-tBu-pyrene gave 2-tBu-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.

Tailoring Colors by O Annulation of Polycyclic Aromatic Hydrocarbons

“…The unpurified perylene mixture was subsequently submitted to a selective C−H borylation reaction in the presence of 10 mol % of [{Ir(COD)(OMe)} 2 ] (COD=1,5‐cyclooctadiene) catalyst and 20 mol % of 4,4′‐di‐tert‐butyl‐2,2′‐bipyridyl (dtbpy) and B 2 pin 2 (pin=pinacolato) in n ‐hexane at 80 °C for 24 h,61 which allowed the isolation of tetra‐ tert ‐butylperylene 1 a as well as mono‐ and bis‐boronic esters 1 b and 1 c (for X‐ray structure, see Supporting Information) in 33, 20 and 30 % yield, respectively. Oxidation of boronic ester 1 b with H 2 O 2 and NaOH in THF at RT62 yielded perylenol derivative 2 in 80–85 % yield. Following the literature synthetic routes for preparing BINOLs,46, 47, 48, 49, 50, 51, 52, 54, 55, 63 we turned our attention toward Cu/TMEDA‐based (TMEDA= N , N , N′ , N′ ‐tetramethylethylenediamine) oxidative C−C bond formation64, 65 as dimerization reaction.…”

Recent developments in and perspectives on three-coordinate boron materials: a bright future

“…50,91–93 This has allowed us to prepare 2,7-bis(Bpin)pyrene in excellent yield and on a large scale directly from pyrene, and the product can also be readily converted to 2,7-dibromopyrene in the same pot. 94 This has opened up a new avenue in pyrene chemistry by providing an efficient, rapid route to a wide variety of desirable 2,7-pyrene derivatives via simple pyrene reagents which can act as formal nucleophilic or electrophilic partners, respectively, in cross-coupling reactions as well as being useful precursors for classical organic reactions.…”

Nitric oxide diffusion to red blood cells limits extracellular, but not intraphagosomal, peroxynitrite formation by macrophages

“…Fluorescein-boronate (Fl-B) and coumarin-7-boronic acid (CBA) were synthesized in our laboratory as previously described (32)(33)(34)(35) with minor modifications. All other reagents were of research grade quality.…”