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Conformations of highly hindered aryl ethers: XXIII –PMR evidence for preferred conformations and intramolecular π complex formation in nitrophenyl naphthyl ethers
Author(s) -
Lehmann F. Pedro A.
Publication year - 1974
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270060115
Subject(s) - intramolecular force , chemistry , ether , hydrogen bond , aryl , stereochemistry , nitro , molecule , alkyl , organic chemistry
The PMR spectrum of 2‐bromo‐4,6‐dinitrophenyl 2′‐naphthyl ether ( 1 ) is consistent with the preferential adoption of a twist conformation ( 1a ) in which the 6‐nitro group and the 1′‐hydrogen are located endo to the ether link. This preference is explained by the formation of an intramolecular π complex between the 6‐nitro group and the C1′C2′ bond, which is stronger than that formed with the C2′C3′ bond, in accord with their bond orders. This study adduces further evidence in favor of: (a) the adoption of twist conformations by these and related ethers, (b) the importance of intramolecular π complex formation as a conformational influence, (c) the formation of complexes in such cases is with specific portions of, and not the complete, π cloud and (d) indicates that similar effects may be discerned in analogous ethers related to the thyroid hormones.