41976-28-7Relevant academic research and scientific papers
Stereocontrol in radical cyclizations on sugar templates
Lesueur, Catherine,Nouguier, Robert,Bertrand, Michele Paula,Hoffmann, Pascale,De Mesmaeker, Alain
, p. 5369 - 5380 (2007/10/02)
The radical cyclization of alkyl hex-2-enopyranosides provides a stereocontrolled route to fused furanopyranes. The intermediate radical is generated either via the reduction of the appropriate halide by tin hydride or via sulfonyl radical addition to allyl hex-2-enopyranosides. The two methodologies are compared with respect to diastereoselectivity. Stereocontrol is discussed on the basis of conformational preference in the transition state.
Stereoselective Free-Radical Cyclization on a Sugar Template The Suphonyl Radical as a Synthetic Tool for Functionalized Glycosides
Nouguier, Robert,Lesueur, Catherine,Riggi, Enzo de,Bertrand, Michele Paula,Virgili, Albert
, p. 3541 - 3544 (2007/10/02)
The addition of a sulphonyl radical to the external double bond of an allyl glycal generates a pro-chiral carbon radical which adds to the glycal double bond with a high diastereoselectivity.Through three consecutive radical steps, the configurations of three new asymmetric centers are controlled.
Enantiomerically Pure Building Blocks from Sugars, 9. An Expedient Approach to Pyranoid Ene and Enol Lactones by BF3-Catalyzed Peroxidation of Glycal and Hydroxyglycal Esters
Lichtenthaler, Frieder W.,Roenninger, Stephan,Jarglis, Pan
, p. 1153 - 1162 (2007/10/02)
An effective and convenient one-pot procedure, simply involving treatment with boron trifluoride/3-chloroperbenzoic acid (MCPBA), is detailed for the high-yield acquisition of enantiomerically pure dihydropyran-2-ones from mono- and disaccharide-derived glycal and hydroxyglycal esters.An assessment of the scope of the method is given, a total of 17 examples being ample evidence for its preparative utility and apparent generality.Substantiation of the mechanism presented - BF3-promoted removal of the allylic acyloxy group, seizure by MCPBA of the allylcarboxonium ion generated, and fragmentation of the resulting hex-2-enopyranose 1-(3-chloro)perbenzoates on quenching - is provided by characterization of the perester intermediates.Conducting the reaction of glycal esters at room temperature a glycol-type C-1-C-2 bond cleavage occurs instead with the generation of acylated 4,5-dihydroxypentenals.
