TY - JOUR
T1 - Regioselective Friedel–Crafts deacylations of polycyclic aromatic ketones in the pyrene series
AU - Hidmi, Taghreed
AU - Pogodin, Sergey
AU - Bogoslavsky, Benny
AU - Agranat, Israel
N1 - Publisher Copyright:
© 2017, Springer Science+Business Media, LLC.
PY - 2018/2/1
Y1 - 2018/2/1
N2 - 1,3,6,8-tetrabenzoylpyrene (1,3,6,8-Bz4PY) and 1,3,6-tribenzoylpyrene (1,3,6-Bz3PY) were synthesized and their crystal structures were determined. The Friedel–Crafts deacylations in PPA of 1,3,6,8-Bz4PY (at 120–200 °C) and of 1,3,6-Bz3PY (at 80–160 °C) have been studied. The mono-deacylation of 1,3,6-Bz3PY was regioselective and led to three dibenzoylpyrenes in the following order of relative amounts: 1,8-Bz2PY > 1,6-Bz2PY > 1,3-Bz2PY. 1,3,6,8-Bz4PY was resistant to deacylation at 120–160 °C. The deacylations of 1,3,6,8-Bz4PY at 200 °C gave the polycyclic aromatic ketone (PAK) 8H-dibenzo[def,qr]chrysen-8-one (DBCO) via an intramolecular Scholl reaction. Two plausible pathways of the Friedel–Crafts deacylation of 1,3,6,8-Bz4PY to give DBCO are proposed. A density functional theory (DFT) B3LYP/6-311(d,p) computational study of the conformational spaces of 1,3,6-Bz3PY and 1,3,6,8-Bz4PY was performed. The estimated energy barriers of formation of dibenzoylpyrenes by deacylation of 1,3,6-Bz3PY increase in the following order: 1,8-Bz2PY < 1,3-Bz2PY < 1,6-Bz2PY. A mechanism of the Friedel–Crafts deacylation of 1,3,6-Bz3PY in PPA via the respective O-protonated ketone and σ-complexes is presented.
AB - 1,3,6,8-tetrabenzoylpyrene (1,3,6,8-Bz4PY) and 1,3,6-tribenzoylpyrene (1,3,6-Bz3PY) were synthesized and their crystal structures were determined. The Friedel–Crafts deacylations in PPA of 1,3,6,8-Bz4PY (at 120–200 °C) and of 1,3,6-Bz3PY (at 80–160 °C) have been studied. The mono-deacylation of 1,3,6-Bz3PY was regioselective and led to three dibenzoylpyrenes in the following order of relative amounts: 1,8-Bz2PY > 1,6-Bz2PY > 1,3-Bz2PY. 1,3,6,8-Bz4PY was resistant to deacylation at 120–160 °C. The deacylations of 1,3,6,8-Bz4PY at 200 °C gave the polycyclic aromatic ketone (PAK) 8H-dibenzo[def,qr]chrysen-8-one (DBCO) via an intramolecular Scholl reaction. Two plausible pathways of the Friedel–Crafts deacylation of 1,3,6,8-Bz4PY to give DBCO are proposed. A density functional theory (DFT) B3LYP/6-311(d,p) computational study of the conformational spaces of 1,3,6-Bz3PY and 1,3,6,8-Bz4PY was performed. The estimated energy barriers of formation of dibenzoylpyrenes by deacylation of 1,3,6-Bz3PY increase in the following order: 1,8-Bz2PY < 1,3-Bz2PY < 1,6-Bz2PY. A mechanism of the Friedel–Crafts deacylation of 1,3,6-Bz3PY in PPA via the respective O-protonated ketone and σ-complexes is presented.
KW - DFT
KW - Friedel–Crafts deacylation
KW - NMR
KW - X-Ray crystallography
KW - acyl rearrangements, Scholl reaction
KW - polyphosphoric acid
KW - pyrene
UR - http://www.scopus.com/inward/record.url?scp=85026900658&partnerID=8YFLogxK
U2 - 10.1007/s11224-017-1004-1
DO - 10.1007/s11224-017-1004-1
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AN - SCOPUS:85026900658
SN - 1040-0400
VL - 29
SP - 97
EP - 111
JO - Structural Chemistry
JF - Structural Chemistry
IS - 1
ER -