82799-67-5Relevant articles and documents
In quest of reversibility of Friedel-Crafts acyl rearrangements in the pyrene series
Agranat, Israel,Mala’bi, Tahani,Oded, Yaacov Netanel,Kraus, Hanna Daniel
, p. 47 - 60 (2019/12/30)
Friedel-Crafts acyl rearrangements in PPA of diacetylpyrenes (80–120 °C), dibenzoylpyrenes (80–200 °C), and bis(4-flurobenzoyl)pyrenes (80–120 °C) and Scholl reactions in AlCl3/NaCl of dibenzoylpyrenes (140–200 °C) have been studied. The substrates were 1-AcPY, 2-AcPY, 1,3-Ac2PY, 1,6-Ac2PY, 1,8-Ac2PY, 2,7-Ac2PY, 1-BzPY, 1,6-Bz2PY, 1,8-Bz2PY, 1-4FBzPY, 1,6-4FBz2PY, 1,8-4FBz2PY. The mixtures of pyrene, 1-AcPY, 2-AcPY, 1,3-Ac2PY, 1,6-Ac2PY, 1,8-Ac2PY, and 2,7-Ac2PY were separated by HPLC. The following reversible intermolecular isomerizations were established: 1,6-Ac2PY ? 1,8-Ac2PY, 1,6-Bz2PY ? 1,8-Bz2PY, and 1,6-4'FBz2PY ? 1,8-4'FBz2PY, albeit not in high yields. The results substantiate Gore’s 1955 proposition that “The Friedel–Crafts acylation reaction of reactive aromatic hydrocarbons is a reversible process.” The isomerizations reported here differ from the few previously reported completely reversible intramolecular Friedel-Crafts acyl rearrangements. At ≥ 140 °C, in PPA and in AlCl3/NaCl, 1,6-Bz2PY and 1,8-Bz2PY underwent a highly regioselective double Scholl reaction to give pyranthrone (3) and deacylations to 1-BzPy (and pyrene), followed by mono-Scholl reactions to give 8H-dibenzo[def,qr]chrysen-8-one (1), and 11H-indeno[2,1-a]pyren-11-one (2). The formation of 3 and not the expected tribenzo[a,ghi,o]perylene-7,16-dione (4) from 1,8-Bz2PY indicates that 1,8-Bz2PY has first undergone isomerization to 1,6-Bz2PY. The present study confirms the linkage between Friedel-Crafts acyl rearrangements and the Scholl reaction.
Synthesis and structure of 2-substituted pyrene-derived scaffolds
Cabral, Lília I.L.,Henriques, Marta S.C.,Paix?o, José A.,Cristiano, Maria L.S.
supporting information, p. 4547 - 4550 (2017/11/03)
Pyrenes bear a propensity to form fluorescent excimers, and thus this chromophore is often found in sensors and fluorescent probes. 2-Functionalized pyrenes are of particular interest, however the preparation of these scaffolds is not trivial, involving synthetic routes that require 4,5,9,10-tetrahydropyrene as a key intermediate. Herein, the development and optimization of routes for the synthesis of 2-functionalized pyrene-derived building blocks, with potential to be used as tags in the preparation of fluorescent probes, is described. Additionally, the crystal structures of ethyl 4,5,9,10-tetrahydro-2-pyrene-5-oxopentanoate and 2-acetyl-4,5,9,10-tetrahydropyrene revealed distinct conformations of the saturated tetrahydropyrene rings.
1-, 2-, and 4-ethynylpyrenes in the structure of twisted intercalating nucleic acids: Structure, thermal stability, and fluorescence relationship
Filichev, Vyacheslav V.,Astakhova, Irina V.,Malakhov, Andrei D.,Korshun, Vladimir A.,Pedersen, Erik B.
experimental part, p. 9968 - 9980 (2009/10/14)
A postsynthetic, on-column Sonogashira reaction was applied on DNA molecules modified by 2- or 4-io-dophenylmethylglycerol in the middle of the sequence, to give the corresponding ortho- and para-twisted intercalating nucleic acids (TINA) with 1-, 2-, and 4-ethynylpyrene residues. The convenient synthesis of 2- and 4-ethynylpyrenes started from the hydrogenolysis of pyrene that has had the sulfur removed and separation of 4,5,9,10-tetrahydropyrene and 1,2,3,6,7,8-hexahydropyrene, which were later converted to the final compounds by successive Friedel-Crafts acetylation, aromatization by 2,3-dichloro-5,6- dicyano-1,4-benzoquinone, and a Vilsmeier-Haack-Arnold transformation followed by a Bodendorf fragmentation. Significant alterations in thermal stability of parallel triplexes and antiparallel duplexes were observed upon changing the attachment of ethynylpyrenes from para to ortho in homopyrimidine TINAs. Thus, for para-TINAs the bulge insertion of an intercalator led to high thermal stability of Hoogsteen-type parallel triplexes and duplexes, whereas Watson-Crick-type duplexes were destabilized. In the case of ortho-TINA, both Hoogsteen and Watson-Crick-type complexeswere stabilized. Alterations in the thermal stability were highly influenced by the ethynylpyrene isomers used. This also led to TINAs with different changes in fluorescence spectra depending on the secondary structures formed. Stokes shift of approximately 100nm was detected for pyren-2-ylethynylphenyl derivatives, whereas values for 1- and 4-ethynylpyrenylphenyl conjugates were 10 and 40 nm, respectively. In contrast with paraTINAs, insertion of two ortho-TINAs opposite each other in the duplex as a pseudo-pair resulted in formation of an excimer band at 505 nm for both 1- and 4-ethynylpyrene analogues, which was also accompanied with higher thermal stability.
Synthesis and stable-ion studies of regioisomeric acetylnitropyrenes and nitropyrenyl carbinols and GIAO-DFT study of nitro substituent effects on α-pyrenyl carbocations
Laali, Kenneth K.,Arrica, Maria A.,Okazaki, Takao,Bunge, Scott D.
experimental part, p. 6093 - 6105 (2009/05/31)
Several regioisomeric acetylnitropyrenes were synthesized from isomeric acetylpyrenes by mild protic nitration. Nitration of 1-acetylpyrene gave the 3-, 6-, and 8-nitro derivatives (with 8-nitro as the major isomer), from which the corresponding carbinols [NO2-Py-CH(OH)CH3; Py = pyrene] were synthesized. Isomeric 4-acetylnitropyrenes and their corresponding carbinols were synthesized by starting from hexahydropyrene through nitration/aromatization/reduction or aromatization/nitration/reduction sequences. The molecular structures of 4-acetyl-3-nitropyrene and 1-(6-nitropyren-1-yl) ethanol were established by X-ray analysis. Tetrahydropyrene was the starting point for the synthesis of isomeric nitro-2-acetylpyrenes. Low-temperature protonation of 1-acetyl-8-nitropyrene, 4-acetyl-3-nitropyrene, and 2-acetyl-6-nitropyrene in FSO3H/SO 2ClF or in FSO3H/SbF5 (1:1)/SO2ClF resulted in the formation of onium dications (by C=O and NO2 protonation). Charge delocalization (pyrenium ion character) in the carboxonium ions is strongly influenced by the position of the carboxonium group, with the 4-acetyl-3-nitropyrene dication being the most delocalized. Superacid protonation of 1-(3-nitropyren-4-yl)ethanol gave a persistent onium dication rather than an α-pyrenyl carbocation. With all other isolated nitropyrenyl carbinol isomers, low-temperature protonation (with FSO3H/SO 2ClF) led to polymerization within 5 min standing at dry-ice-acetone temperature. For these cases, nitro substituent effects on the α-pyrenyl carbocations were gauged by DFT and GIAO-DFT studies. An interesting relationship between the computed nitro tilt angles and the GIAO-derived charge delocalization modes was observed. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
7-amino-2-pyrenecarboxylic acid
Musa, Abdallah,Sridharan, Bhama,Lee, Hyoyoung,Mattern, Daniell Lewis
, p. 5481 - 5484 (2007/10/03)
Pyrenes undergo initial electrophilic substitution in the 1 position; a second substitution typically occurs in the 3, 6, or 8 positions. We sought a pyrene with synthetically useful handles in the unusual 2,7 substitution pattern. To that end, 7-amino-2-pyrenecarboxylic acid was prepared by partial reduction of pyrene to 4,5,9,10-tetrahydropyrene, Friedel-Crafts acylation in the 2 position, and conversion to 2-carbethoxytetrahydropyrene through the haloform reaction and esterification. Nitration of the ester proceeded in the 7 position; rearomatization, reduction of the nitro group, and saponification gave the title compound.
