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Synthesis and Conformational Properties of Nonsymmetric Pillar[5]arenes and Their Acetonitrile Inclusion Compounds
Author(s) -
Kou Yuhui,
Tao Hongqi,
Cao Derong,
Fu Zhiyong,
Schollmeyer Dieter,
Meier Herbert
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201000718
Subject(s) - chemistry , steric effects , benzene , acetonitrile , pillar , molecule , yield (engineering) , alkoxy group , crystallography , crystal structure , computational chemistry , stereochemistry , organic chemistry , alkyl , materials science , structural engineering , engineering , metallurgy
The catalytic cyclocondensation of 1‐butoxy‐4‐methoxy‐2,5‐bis(methoxymethyl)benzene ( 1d ) affords a statistical mixture of the regioisomeric pillar[5]arenes 3a – d in high yield. The alkoxy groups are arranged stereoselectively in a mode so that they avoid steric interactions. The rotation of the benzene rings is, at room temperature, fast in terms of the NMR timescale and leads to a de facto C s symmetry for 3a – c and a C 5 h symmetry for 3d . All four structural isomers can encapsulate two CH 3 CN guest molecules. The structure determinations are based on four crystal structure analyses (constitutions) and NMR spectroscopic measurements (conformations).