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In quest of reversibility of Friedel-Crafts acyl rearrangements in the pyrene series
Structural Chemistry ( IF 2.1 ) Pub Date : 2019-12-16 , DOI: 10.1007/s11224-019-01460-4
Israel Agranat , Tahani Mala’bi , Yaacov Netanel Oded , Hanna Daniel Kraus

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 AlCl 3 /NaCl of dibenzoylpyrenes (140–200 °C) have been studied. The substrates were 1-AcPY , 2-AcPY, 1,3-Ac 2 PY , 1,6-Ac 2 PY , 1,8-Ac 2 PY , 2,7-Ac 2 PY , 1-BzPY , 1,6-Bz 2 PY , 1,8-Bz 2 PY , 1-4FBzPY , 1,6-4FBz 2 PY , 1,8-4FBz 2 PY . The mixtures of pyrene, 1-AcPY , 2-AcPY , 1,3-Ac 2 PY , 1,6-Ac 2 PY , 1,8-Ac 2 PY , and 2,7-Ac 2 PY were separated by HPLC. The following reversible intermolecular isomerizations were established: 1,6-Ac 2 PY ⇌ 1,8-Ac 2 PY , 1,6-Bz 2 PY ⇌ 1,8-Bz 2 PY , and 1,6-4'FBz 2 PY ⇌ 1,8-4'FBz 2 PY , 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 AlCl 3 /NaCl, 1,6-Bz 2 PY and 1,8-Bz 2 PY 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 8 H -dibenzo[ def,qr ]chrysen-8-one ( 1 ), and 11 H -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-Bz 2 PY indicates that 1,8-Bz 2 PY has first undergone isomerization to 1,6-Bz 2 PY . The present study confirms the linkage between Friedel-Crafts acyl rearrangements and the Scholl reaction.

中文翻译:

探索芘系列中 Friedel-Crafts 酰基重排的可逆性

PPA 中二乙酰芘 (80–120 °C)、二苯甲酰基芘 (80–200 °C) 和双 (4-氟苯甲酰基) 芘 (80–120 °C) 的 Friedel-Crafts 酰基重排和 AlCl 3 /NaCl 中的 Scholl 反应已经研究了二苯甲酰芘(140-200°C)。底物为 1-AcPY、2-AcPY、1,3-Ac 2 PY、1,6-Ac 2 PY、1,8-Ac 2 PY、2,7-Ac 2 PY、1-BzPY、1,6 -Bz 2 PY , 1,8-Bz 2 PY , 1-4FBzPY , 1,6-4FBz 2 PY , 1,8-4FBz 2 PY 。通过HPLC分离芘、1-AcPY、2-AcPY、1,3-Ac 2 PY、1,6-Ac 2 PY、1,8-Ac 2 PY 和2,7-Ac 2 PY 的混合物。建立了以下可逆分子间异构化:1,6-Ac 2 PY ⇌ 1,8-Ac 2 PY 、1,6-Bz 2 PY ⇌ 1,8-Bz 2 PY 和 1,6-4'FBz 2 PY ⇌ 1,8-4'FBz 2 PY ,尽管收率不高。结果证实了戈尔 1955 年的命题,即“活性芳烃的弗里德尔-克拉夫茨酰化反应是一个可逆过程”。这里报道的异构化不同于之前报道的少数完全可逆的分子内弗里德尔-克拉夫茨酰基重排。在 ≥ 140 °C 时,在 PPA 和 AlCl 3 /NaCl 中,1,6-Bz 2 PY 和 1,8-Bz 2 PY 经历了高度区域选择性的双 Scholl 反应生成吡喃酮 (3) 并脱酰基生成 1-BzPy (和芘),然后进行单-Scholl 反应,得到 8 H -dibenzo[ def,qr ]chrysen-8-one ( 1 ) 和 11 H -indeno[2,1-a ]pyren-11-one ( 2 ) . 从 1,8-Bz 2 PY 形成 3 而不是预期的三苯并 [a,ghi,o] 苝-7,16-二酮 (4) 表明 1,8-Bz 2 PY 首先异构化为 1, 6-Bz 2 PY。
更新日期:2019-12-16
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