Synthesis of C‐Disaccharides through a One‐Pot Alkynol Cycloisomerization‐Reductive Deoxygenation

Abstract

A sweet disposition: Simple protocols for the synthesis of (1→1)‐ and (1→6)‐linked C‐disaccharides have been developed (see scheme). A one‐pot Au‐catalyzed alkynol cycloisomerization followed by BF3⋅Et2O, Et3SiH reduction has been established as the key reaction for C‐disaccharide synthesis including all possible pyran–pyran, furan–furan, and pyran–furan combinations.

Recent Advances in the Chemical Synthesis of C-Glycosides

“…Introduction of ethynyl groups onto sugar lactones involved nucleophilic addition with lithium (trimethylsilyl)­acetylide in the presence of CeCl 3 and deoxygenation with Et 3 SiH and BF 3 ·OEt 2 ; subsequent desilylation with aqueous NaOH led to β-alkynyl glycosides 595 – 597 in good yields (Scheme ). − …”

Synthesis of CH2-Linked α(1,6)-Disaccharide Analogues by α-Selective Radical Coupling C-Glycosylation

“…However, synthesis of C -linked disaccharide analogues with a native sugar structure, differing only in the glycosidic bond, is still cumbersome. Specifically, construction of the C -glycosidic linkage and transformation into the disaccharide skeleton are usually performed separately. − We believe that, as with standard O -glycosylation, a C -glycosylation reaction capable of directly connecting stable donor and acceptor building blocks would facilitate the preparation of a variety of glycoconjugates analogues useful in biological studies. Here we report a unique strategy to synthesize CH 2 -linked (1,6)-disaccharides analogues by direct C -glycosylation reaction.…”

“…Reported syntheses of C -linked (1,6)-disaccharide analogues include an elegant and flexible synthetic methodology that was developed by Werz and co-workers. , A variety of α- and β-linked (1,6)- C -disaccharides 1α and 1β have been successfully obtained by functional group manipulation from the common intermediates 2 , constructed by Sonogashira coupling of the C1-sp 2 hybridized donor 3 without the 2-substituent and alkyne acceptor 4 (Scheme -1b). On the other hand, direct C -glycosylation using a C1-sp 3 hybridized donor , is expected to be more powerful and efficient.…”