Abstract
The reaction of t-butylmagnesium chlorides with diastereomerically pure (R)-1,2-O-isopropylidene-3,5-O-sulfinyl-α-d-glucofuranose (R)-4 was found to be stopped at the stage of the corresponding, diastereoisomerically pure 1,2-O-isopropylidene-(5-O-α-d-glucofuranosyl) t-butanesulfinate (S)-10 for which the crystal structure and the (S)-absolute configuration was determined by X-ray crystallography. Comparison of the absolute configurations of the starting sulfite (R)-4, and t-butanesulfinate (S)-10 (which crystallizes in the orthorhombic system, space group P212121, with the single compound molecule present in the asymmetric unit), clearly indicates that the reaction of nucleophilic substitution at the stereogenic sulfur atom in the sulfite (R)-4 occurs with the full inversion of configuration via the trigonal bipyramidal sulfurane intermediate 4c in which both the entering and leaving groups are located in apical positions.
Highlights
It is worth noting that very recently diasteroisomerically pure sulfinate 3a was isolated in almost quantitative yield by reacting p-toluenesulfinyl chloride 1a with (-)-(1R,3S,5R)-menthol in the absence of a base as an HCl scavenger [17], while all attempts of its isolation under flow conditions resulted in the formation of 2a/3a mixtures [18]
In the the search search for for an analternative alternative and and new new procedure procedure for for the thepreparation preparation ofof diastereomeric diastereomeric sulfinates derived from readily available sugars, we focused our attention on diastereomerically sulfinates derived from readily available sugars, we focused our attention on diastereomerically diastereomerically sulfinates derived from readily available sugars, we focused our attention on diastereomerically pure (R)-1,2-O-isopropylidene-3,5-O-sulfinyl-αD-glucofuranose (R)-4 (R)-4[28][28]
[28], we decided to check if its (R)-1,2-O-isopropylidene-3,5-O-sulfinyl-αreactions with Grignard glucofuranose (R)-4, synthesized from αD
Summary
Racemic and optically active diastereoisomeric and/or enantiomeric sulfinic esters played a very important role in the development of sulfur chemistry and especially sulfur stereochemistry [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]. The reaction of this diastereoisomeric sulfinates with organometallic tolyl sulfoxide. The reaction of this diastereoisomeric sulfinates with organometallic reagents has been commonly applied toto obtain a a very richpure family of reagents has been commonly applied obtain a very rich family enantiomerically sulfoxides organometallic reagents has been applied organometallic reagents has beento commonly commonly applied to ofobtain obtain a very very rich rich family family of of enantiomerically pure sulfoxides and other sulfinyl derivatives as “Andersen synthesis”. The best results were obtained diastereomeric which are substrates for of diastereomeric sulfinates, which areused usedagain again as substrates forthe thesynthesis synthesis ofenantiomerically enantiomerically pure sulfinyl derivatives. Molecules 2020, 25, x FOR PEER REVIEW sulfites 5 with t-butylmagnesium chloride carried out in the presence of optically active aminoalcohols as a chiral complexing agent (Scheme 3) [30]
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