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Flexible Molecules with Defined Shape, VII. Conformational Analysis of 3,5‐Dimethylhexene Derivatives, Subunits of Polyketide Derived Natural Products
Author(s) -
Göttlich Richard,
Schopfer Ulrich,
Stahl Martin,
Hoffmann Reinhard W.
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970819
Subject(s) - chemistry , steric effects , conformational isomerism , polyketide , stereochemistry , residue (chemistry) , molecule , methyl group , group (periodic table) , organic chemistry , enzyme , biosynthesis
2,4‐Dimethylpentane ( 1 ) is a typical biconformational backbone segment. When one methyl group in 1 is replaced by a sp 2 bound residue (vinyl, formyl, phenyl), as in compounds 3–6 , a small preference for conformer 2b ensues, in which the sp 2 bound group resides in the sterically more hindered position. Oxygen substituents in the 3‐position do not change this conformational preference, but in concert with bulkier sp 2 ‐hybridized groups in the 2‐position, a preference for the 2a backbone conformation may be induced, in which the sp 2 ‐hybridized group is in the less sterically hindered end‐of‐chain position, cf. compounds 20 and 23 .