SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• destabilizing electron-withdrawing carboxy group flanking atom C-2 and the lack of a participating auxiliary in position C-3 of 5. Glycal 24 is widely used for α-sialylation by utilizing neighboring group participation and site-selective fluorination at C-3 [12][13][14][41]. Moreover, it is the main precursor

Automated solid-phase synthesis of oligosaccharides containing sialic acids

• Chian-Hui Lai,
• Heung Sik Hahm,
• Chien-Fu Liang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2015, 11, 617–621, doi:10.3762/bjoc.11.69

• 10.3762/bjoc.11.69 Abstract A sialic acid glycosyl phosphate building block was designed and synthesized. This building block was used to prepare α-sialylated oligosaccharides by automated solid-phase synthesis selectively. Keywords: α-sialylation; automated synthesis; glycosylation; sialic acid; solid

• , building block 4 was more reactive than 5 as the synthesis of disaccharide 13 resulted almost in full α-sialylation as observed by HPLC analysis of the crude product following photocleavage from the resin that showed only one peak while 12 was not the only product. Disaccharide 12 was obtained in 30% and

Acid- mediated reactions under microfluidic conditions: A new strategy for practical synthesis of biofunctional natural products

• Katsunori Tanaka and
• Koichi Fukase

Beilstein J. Org. Chem. 2009, 5, No. 40, doi:10.3762/bjoc.5.40

• preparing bioactive natural products [27][28][29][30][31][32][33]. Our successful examples are cation-mediated reactions, such as α-sialylation [28][32], β-mannosylation [31], and reductive opening of the benzylidene acetal groups in sugars [30], for which improved procedure under the microfluidic

• complex oligosaccharides has yet to be established in terms of (i) selectivity in the glycosyl bond formations, i.e., β-mannosylation and α-sialylation, and (ii) a non-tedious purification process during each step of glycosylation and deprotection. Our interests in elucidating unknown biological functions

• the N-glycan structures. Herein, two challenging glycosyl bond formations, i.e., β-mannosylation and α-sialylation, were carried out in advance in solution, by the aid of the microfluidic systems (Figure 1) [28][31][32]. The problem of the key protecting group manipulation, i.e., the reductive opening