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Synthesis, Structures and Lewis‐Acid‐Induced Isomerization of 8‐Methoxy[2.2]metaparacyclophanes and a DFT Study
Author(s) -
Islam Md. Monarul,
Feng Xing,
Rahman Shofiur,
Georghiou Paris E.,
Matsumoto Taisuke,
Tanaka Junji,
Alodhayb Abdullah,
Redshaw Carl,
Yamato Takehiko
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201900190
Subject(s) - isomerization , chemistry , benzene , pyrene , lewis acids and bases , medicinal chemistry , molecule , stereochemistry , catalysis , organic chemistry
Methyl substituted 8‐methoxy[2.2]MPCPs 8 a – b were obtained via the corresponding thiacylophanes and its oxidized products. Lewis acid‐catalyzed (AlCl 3 ‐MeNO 2 ) reactions of 5‐ tert ‐butyl‐8‐methoxy‐12,13,15,16‐tetramethyl[2.2]MPCP 8 b under various conditions led to transannular cyclization and isomerization reactions, affording the considerably less‐strained 5‐ tert ‐butyl‐8‐methoxy[2.2]MPCP 9 , 5‐ tert ‐butyl‐8‐hydroxy‐14,16,17,18‐tetramethyl[2.2]metacyclophane 10 and pyrene derivatives 11 and 12 . However, on prolonging the reaction time to 3 h for 8 b , the major product is 5‐ tert ‐butyl‐8‐hydroxy[2.2]MPCP 10 . These reactions are strongly affected by the size and properties of the C‐8 substitutents as well as the methyl substitutents on the para‐ linked benzene rings, which increase the strain in the molecules. The 1 H NMR spectra and X‐ray crystallographic analysis of 8 b revealed that it adopts a syn‐ conformation both in solution and in the solid state.