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 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.
