Protective group-free synthesis of 3,4-dihydroxytetrahydrofurans from carbohydrates: formal total synthesis of sphydrofuran

Delineating The Multiple Roles of B(C6F5)3 in the Chemoselective Deoxygenation of Unsaturated Polyols

“…C 5 sugars react similarly with B(C 6 F 5 ) 3 , and pretreatment provides tetrahydrofurans. 12 Addition of Et 3 SiH to these solutions led to preferential S N 2′ reduction of the allylic silyl ether (∼75:25; entries 5−7, Table 1). Reducing the temperature and adding B(C 6 F 5 ) 3 and Et 3 SiH together to 7 improved the S N 2′ selectivity to 91:9 for syn-triol 13, though the role of precyclization is not clear in this case (entry 7).…”

Chemoselective Reactions for the Synthesis of Glycoconjugates from Unprotected Carbohydrates

“…Wittig-and HWE-type reactions have also been applieda t the reducing ends of unprotectedaldoses to providet he corre-sponding polyhydroxyalkyl olefinic derivatives. [221] However,t o the best of our knowledge,s uch methodologies did not afford glycosides and thus are outside the scope of this review.…”

Unprotected Carbohydrates as Starting Material in Chemical Synthesis: Not Just a Challenge but an Opportunity

“…8a Recently, Wittig olefination of unprotected monosaccharides was utilized as a key step in the formal total synthesis of sphydrofuran. 9 A modified Wittig procedure, the Horner-Wadsworth-Emmons reaction, has likewise been applied to unprotected carbohydrates giving access to C-glycosides optimally under solvent-free conditions. 10…”

“…8a Recently, Wittig olefination of unprotected monosaccharides was utilized as a key step in the formal total synthesis of sphydrofuran. 9 A modified Wittig procedure, the Horner-Wadsworth-Emmons reaction, has likewise been applied to unprotected carbohydrates giving access to C-glycosides optimally under solvent-free conditions. 10 Scheme 2 Synthesis of polyhydroxylated lactone by Wittig reactionhydrogenation sequence from unprotected D-mannose Tin-mediated allylation of unprotected carbohydrates as a method to extend the carbon chain by three carbon atoms was exploited for the first time in 1991 by Schmid and Whitesides.…”