Recent advances in reagent-controlled stereoselective/stereospecific glycosylation

Facile Anomer-oriented Syntheses of 4-Methylumbelliferyl Sialic Acid Glycosides

“…Our novel α-sialylation approach combines concepts of in situ anomerisation method introduced by Lemieux with contemporary reagent-controlled glycosylation techniques. [41][42][43] Excellent to good yields and α-stereoselectivity was observed for all the C-5 functionalised sialic derivatives; consistent with the belief that the glycerol side chain (conserved for all of our analogues in this case) conformation of nonulosonic acids can determine the stereochemical outcome during glycosylation reactions. 29,30,44 Similarly, the β-anomers were selectively synthesised via a preferential diastereoselective addition reaction to our C-5 derivatised neuraminic acid glycal analogues.…”

Guidelines for O-Glycoside Formation from First Principles

“…Many other additives have been investigated, 106 − 108 and an increasing number have been spectroscopically 46 and in rare cases even crystallographically 109 characterized. The most promising in recent years appears to be a series of tertiary formamides, with DMF as the prototypical example and varying in size and electronic character of the N -substituents.…”

Palladium-Catalyzed O - and N -Glycosylation with Glycosyl Chlorides

“…K 2 CO 3 (99%, J&K Chemical, Beijing, China) and Pd(OAc) 2 (98%, J&K Chemical) were used in all Pd-catalyzed glycosylation reactions. NMR spectra were recorded on Bruker AVANCE AV 400 instruments, and all NMR experiments are reported in units of parts per million (ppm), using residual solvent peaks [chloroform (δ = 7.26 ppm) or tetramethylsilane (TMS) (δ = 0.00 ppm) for 1 H NMR, chloroform (δ = 77.16 ppm) for 13 C NMR] as internal reference.…”

“…[1][2][3][4][5][6] Over the past century, synthetic carbohydrate chemistry has been greatly advanced to enable the formation of various O-, N-, C-, and S-linked glycosidic bonds in high efficiency and with excellent regio-and stereochemical control. [7][8][9][10][11][12][13] A large number of carbohydrates of highly complex structures have been successfully constructed even in automated fashion. However, many difficult challenges in glycosylation chemistry remain to be addressed.…”