Synthesis 2016; 48(02): 213-222
DOI: 10.1055/s-0035-1560323
paper
© Georg Thieme Verlag Stuttgart · New York

Efficient Synthesis of a High-Mannose-Type Pentasaccharide and Hexasaccharide Related to N-Glycans

Rui Jiang
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
,
Xiao-mei Liang
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
,
Shu-hui Jin*
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
,
Hui-zhe Lu
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
,
Yan-hong Dong
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
,
Dao-quan Wang
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
,
Jian-jun Zhang*
Department of Applied Chemistry, China Agricultural University, Beijing 100193, P. R. of China   Email: shuhuij@cau.edu.cn   Email: zhangjianjun@cau.edu.cn
› Author Affiliations
Further Information

Publication History

Received: 20 July 2015

Accepted after revision: 31 August 2015

Publication Date:
28 October 2015 (online)


Abstract

Two high-mannose-type N-glycans, Man5 and Man6 oligosaccharides, were concisely synthesized from 4-methoxyphenyl α-d-mannopyranoside via 9 and 12 steps, and in 23% and 15% overall yields, respectively. The efficiency of the synthesis relies on the large-scale preparation of a key disaccharide intermediate, 4-methoxyphenyl 3,6-di-O-allyloxycarbonyl-2,4-di-O-benzoyl-α-d-mannopyranosyl-(1→6)-2,4-di-O-benzoyl-α-d-mannopyranoside, with two hydroxyl groups partially masked by allyloxycarbonyl protection. The disaccharide was obtained in 84% yield by regioselective glycosylation of 4-methoxyphenyl 2,4-di-O-benzoyl-α-d-mannopyranoside with 3,6-di-O-allyloxycarbonyl-2,4-di-O-benzoyl-α-d-mannopyranosyl trichloroacetimidate. The disaccharide could be easily transformed to a tetrasaccharide diol acceptor via condensation of 4-methoxyphenyl 3,6-di-O-allyloxycarbonyl-2,4-di-O-benzoyl-α-d-mannopyranosyl-(1→6)-2,4-di-O-benzoyl-α-d-manno­pyranoside with a disaccharide donor followed by removal of the two allyloxycarbonyl groups in the resultant tetrasaccharide, or be converted into a triol acceptor by direct deallyloxycarbonylation. Glycosylation of the triol or diol acceptor with 2,3,4,6-tetra-O-benzoyl-α-d-manno­pyranosyl trichloroacetimidate provided the desired protected pentasaccharide and hexasaccharide in one step in 64% and 67% yields, respectively. Finally, the target compounds, pentasaccharide and hexasaccharide, were obtained after deprotection. The structures of target compounds and intermediates were characterized by 1H NMR, 13C NMR, and HRMS.

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