Sulfenate esters as glycosyl acceptors: A novel approach to the synthesis of 2-deoxyglycosides

Glycosylation with 2′-thio-S-acetyl participation

“…As expected, 11 proved to be identical with the literature compound, 15 according to its 1 H NMR spectrum at 500 MHz. The structure of the triacetate/tribenzoate 10, whose 1 H NMR spectrum closely resembles that of the corresponding disaccharide hexaacetate, 16 was further corroborated by conversion to the hexaacetate itself (NaOMe, MeOH; then Ac 2 O, pyridine, DMAP; 90% overall), and then comparison of its 1 H NMR spectrum with the reported values.…”

Special Problems in Glycosylation Reactions: 2‐Deoxy Sugars

“…Franck [54] applied this methodology to the synthesis of an aureolic acid disaccharide made of two 2,6-dideoxy sugars with a p-(1-3) linkage. This approach is strongly reminiscent of the reaction reported by Ito and Ogawa [55], where phenylsulfenate esters are added to glycals in the presence of TMS triflate to give mainly P-glycosides ( Figure 4). But although a similar attack of the TMS-activated sulfenate on the glycal is occurring, a close interaction between aglycon and glycal is not required here.…”

“…The 2'-deoxy-2'-iodo-Pdisaccharides (57) were obtained in high yield and with a stereoselectivity often higher than 9: 1. The high levels of stereochemical control in glycosylations with either a-iodoacetates (46) or P-iodoacetates (55) are undoubtedly due to the fact that corresponding iodonium ions of type 4 or 5 respectively are configurationally stable under the glycosylation conditions (TMSOTf, low temperatures); no equilibration of these ions occurs.…”

Electrochemical synthesis and X-ray crystal structures of β-d-2-phenylselenyl-1,3,4,6-tetra-O-acetylglucopyranose and α-d-2-phenylselenyl-1,3,4,6-tetra-O-acetylmannopyranose

“…Among 2-substituted monosaccharide derivatives, which can be synthesized from glycals those containing halogens, 1-7 sulfur, and selenium [8][9][10][11][12][13][14][15][16] are synthetically useful because they can be readily transformed to other derivatives. Saccharides containing a phenylselenyl group are particularly interesting, since this group can be removed by both reductive and oxidative methods, resulting in 2-deoxysugars or unsaturated sugars, respectively.…”