550
3
Chemical Glycosylation Reactions
⊡ Scheme 58
(Ref. [68,69])
⊡ Scheme 59
(Ref. [70])
syl 4-pentenoates as donors ( > Scheme 57 and > Scheme 58) [69]. Moreover, they described
a highly reactive and stereoselective procedure for the β-mannopyranosylation employing 4,6O-benzylidene mannopyranosyl pentenoate and PhSeOTf ( > Scheme 59), and this method was
proved to be comparable to and even better than other methods for the β-mannosylation of the
simple reactive primary alcohols [70]. On the other hand, the reactivity and stereoselectivity
of 4-pentenoic acid ester of N-acetylneuraminic acid as a sialyl donor were also investigated with a series of promoters, such as NIS-TESOTf, dimethyl(methylthio)sulfonium triflate
(DMTST), and IDCP, but the glycosylation with the sialyl pentenoate gave the O-sialosides in
low yield and low stereoselectivity ( > Scheme 60) [71].
3
Chemical Glycosylation Reactions
⊡ Scheme 58
(Ref. [68,69])
⊡ Scheme 59
(Ref. [70])
syl 4-pentenoates as donors ( > Scheme 57 and > Scheme 58) [69]. Moreover, they described
a highly reactive and stereoselective procedure for the β-mannopyranosylation employing 4,6O-benzylidene mannopyranosyl pentenoate and PhSeOTf ( > Scheme 59), and this method was
proved to be comparable to and even better than other methods for the β-mannosylation of the
simple reactive primary alcohols [70]. On the other hand, the reactivity and stereoselectivity
of 4-pentenoic acid ester of N-acetylneuraminic acid as a sialyl donor were also investigated with a series of promoters, such as NIS-TESOTf, dimethyl(methylthio)sulfonium triflate
(DMTST), and IDCP, but the glycosylation with the sialyl pentenoate gave the O-sialosides in
low yield and low stereoselectivity ( > Scheme 60) [71].