Publication

Stabilizing Effect by Geminal Dioxy Substitution and Anomeric Effect in 3,6-Dihydro-6-Methoxy-1,2-Oxathiin 2-Oxides

Pierre Vogel
1993
Journal Articles

Abstract

The hetero-Diels-Alder addition Of SO2 to (E)-hexa-1,3-diene (4) gives first 6-ethyl-3,6-dihydro-1,2-oxathiin 2-oxide (= 6-ethylsultine) with the Et group occupying a pseudoaxial position, and then the more stable stereoisomer 6 with the Et substituent in a pseudoequatorial position. The SO2 additions to 1-methoxybuta-1,3-diene (7) and to 1-methoxy-3-[(trimethylsilyl)oxy]buta-1,3-diene (8) give the 6-methoxysultines 9 and 10, respectively, with the MeO groups in pseudoaxial positions and which do not equilibrate with sultines having pseudoequatorial MeO substituents (anomeric effect). A lower limit of DELTADELTAG = 3.9 kcal/mol was evaluated at -60-degrees for the stabilizing effect arising from the geminal vicinity of a MeO and sulfinate moiety in 3,6-dihydro-6-methoxy-4-[(trimethylsilyl)oxy]-1,2-oxathiin 2-oxide.

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https://infoscience.epfl.ch/entities/publication/52f16f30-9cc3-4cdf-9d42-f7a454b41804

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Pierre Vogel
1993
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/52f16f30-9cc3-4cdf-9d42-f7a454b41804

About this result

Related concepts (13)

Anomeric effect

In organic chemistry, the anomeric effect or Edward-Lemieux effect is a stereoelectronic effect that describes the tendency of heteroatomic substituents adjacent to a heteroatom within a cyclohexane ring to prefer the axial orientation instead of the less hindered equatorial orientation that would be expected from steric considerations. This effect was originally observed in pyranose rings by J. T. Edward in 1955 when studying carbohydrate chemistry. The term anomeric effect was introduced in 1958.

Carbohydrate conformation

Carbohydrate conformation refers to the overall three-dimensional structure adopted by a carbohydrate (saccharide) molecule as a result of the through-bond and through-space physical forces it experiences arising from its molecular structure. The physical forces that dictate the three-dimensional shapes of all molecules—here, of all monosaccharide, oligosaccharide, and polysaccharide molecules—are sometimes summarily captured by such terms as "steric interactions" and "stereoelectronic effects" (see below).

Anomer

In carbohydrate chemistry, a pair of anomers () is a pair of near-identical stereoisomers or diastereomers that differ at only the anomeric carbon, the carbon that bears the aldehyde or ketone functional group in the sugar's open-chain form. However, in order for anomers to exist, the sugar must be in its cyclic form, since in open-chain form, the anomeric carbon is planar and thus achiral. More formally stated, then, an anomer is an epimer at the hemiacetal/hemiketal carbon in a cyclic saccharide.

Related publications (1)

Stabilizing Effect by Geminal Dioxy Substitution and Anomeric Effect in 3,6-Dihydro-6-Methoxy-1,2-Oxathiin 2-Oxides

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