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Properties and reactions of 1,3-oxathianes - IV: the difference in the conformational energies of axial methyl groups in positions 4 and 6

✍ Scribed by Paavo Pasanen; Kalvi Pihlaja

Publisher: Elsevier Science
Year: 1971
Tongue: French
Weight: 130 KB
Volume: 12
Category: Article
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(01)97516-1

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✦ Synopsis

Conformational ;f;ects in 1,3-dioxans and 1,3-dithianes have been recently largely elucidated. -That is why we started a systematic study of alkyl-substituted 1,3-oxathianes to compare their conformational features with those of their above-mentioned symmetric analogs.

GELAN and ANTEURIS investigated the equilibrium between the conformational isomers of trans-4,6-dimethyl-1,3-oxathiane with the aid of coupling constants. They came to the result that the conformation with an axial 4-methyl group is about 1.1 kcal/mol more stable than that with an axial 6-methyl group (Fig. 1;

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