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Dynamic stereochemistry at sp 2 sp 3 bonds part 1—the use of heterocyclic models for quantitative studies of steric effects of alkyl groups
Author(s) -
Roussel Christian,
Gallo Roger,
Metzger Jacques,
Sandström Jan
Publication year - 1980
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.1270140208
Subject(s) - steric effects , chemistry , substituent , alkyl , stereochemistry , computational chemistry , organic chemistry
The barriers to rotation of the 3‐substituent in six 3‐RCH 2 ‐4‐Me‐δ 4 ‐thiazoline‐2‐thiones (R Me, Et, Pr, Isobu, Isopr, t ‐Bu) and in two analogous methiodides have been measured by the 1 H DNMR technique. The barriers are discussed in relation to the possible conformations of the transition states, and comparisons are made with barriers to rotation of the same substituents in other frameworks. It is concluded that the relative steric effects are strongly dependent on the framework and that, in general, a conformational analysis of the individual cases is necessary to understand the steric effects of alkyl groups.