Rare earth perchlorate catalyzed glycosidation of glycosyl fluorides with trimethylsilyl ethers

Triflic Acid Catalyzed Reductive Coupling Reactions of Carbonyl Compounds with O‐, S‐, and N‐Nucleophiles

“…[16] To promote the reactivities of the cerium salts further, we chose nitromethane as solvent. [17] Out of a range of different ceriumA C H T U N G T R E N N U N G (III) salts, ceriumA C H T U N G T R E N N U N G (III) perchlorate hexahydrate [18] (5 mol %) catalysed the reductive etherification of benzaldehyde (1) to dibenzyl ether (2) with triethylsilane in short reaction times and high yields ( Table 1, entry 4). Interestingly, ceriumA C H T U N G T R E N N U N G (III) triflate [19] was less efficient (Table 1, entry 2), whereas CeCl 3 [20] showed only very low activity (Table 1, entry 3).…”

Strategien zur Erforschung neuer Reaktionen

“…Ein besonders nützliches, nichtexplosives Reagens, das im KilogrammMengen erhältlich ist, ist das von Lal und Mitarbeitern entwickelte Deoxofluor. [117] Aktivierende Reagentien für Glycosylierungen mit Glycosylfluorid wurden in ähnlich großer Zahl entwickelt; Beispiele sind SnCl 2 /AgClO 4 , [102] SnCl 2 /TrClO 4 , [107] SnCl 2 / AgOTf, [128] SiF 4 , [129] Me 3 SiOTf, [129] BF 3 ·OEt 2 , [130] [133,134] Bu 2 Sn(ClO 4 ) 2 , [135] Me 2 GaCl, [136] Tf 2 O, [137] LiClO 4 , [138] Yb(OTf) 3 , [139] La(ClO 4 ) 3 ·n H 2 O, [140] La(ClO 4 ) 3 ·n H 2 OSn(OTf) 2 , [141] Yb-Amberlyst 15, [142] sulfatiertes Zirconiumdioxid, [143] TrB(C 6 F 5 ) 4 , [144,145] TfOH, [145][146][147] HClO 4 , [147] HB(C 6 F 5 ) 4 , [147] Carbokationen (B(C 6 F 5 ) 4 À -und TfO À -Salze), [148] SnCl 2 /AgB(C 6 F 5 ) 4 , [149] SnCl 4 /AgB(C 6 F 5 ) 4 , [150] Ce(ClO 4 ) 3 . [151] Unser ursprünglicher Aktivator, SnCl 2 / AgClO 4 , wurde erfolgreich in der Totalsynthese von Glycosphingolipiden (Schema 37) [152,153] und von Cyclodextrin (Schema 38) eingesetzt.…”

Explorations into New Reaction Chemistry

“…Activating reagents for glycosylations with glycosyl fluoride have been studied intensively and various types of reagents have been developed such as SnCl 2 /AgClO 4, 102 SnCl 2 /TrClO 4, 107 SnCl 2 /AgOTf,128 SiF 4 ,129 Me 3 SiOTf,129 BF 3 ⋅OEt 2 ,130 TiF 4 ,131 SnF 4 ,131 [Cp 2 MCl 2 ]/AgClO 4 (M=Ti, Zr, Hf; Cp=cyclopentadiene),132 [Cp 2 ZrCl 2 ]/AgBF 4 133 [Cp 2 HfCl 2 ]/AgOTf,133, 134 Bu 2 Sn(ClO 4 ) 2 ,135 Me 2 GaCl,136 Tf 2 O,137 LiClO 4 ,138 Yb(OTf) 3 ,139 La(ClO 4 ) 3 ⋅ n H 2 O,140 La(ClO 4 ) 3 ⋅ n H 2 O/Sn(OTf) 2, 141 Yb/Amberlyst 15,142 sulfated zirconia,143 TrB(C 6 F 5 ) 4 ,144, 145 TfOH,145–147 HClO 4 ,147 HB(C 6 F 5 ) 4 ,147 carbocations (B(C 6 F 5 ) 4 − and TfO − salts),148 SnCl 2 /AgB(C 6 F 5 ) 4 ,149 SnCl 4 /AgB(C 6 F 5 ) 4 ,150 Ce(ClO 4 ) 3 151. Our original activator, SnCl 2 /AgClO 4, was effectively applied in the synthesis of several types of glycosphingolipids (Scheme )152, 153 and of cyclodextrin (Scheme ) 154.…”