Acetyl migration in the monoacetates of methyl 6-O-trityl-α-D-glucopyranoside

Casinovi, C. G.; Framondino, M.; Randazzo, G.; Siani, Francesco

doi:10.1016/s0008-6215(00)81993-x

Cited by 15 publications

(3 citation statements)

References 9 publications

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“…302 Notably, a comparable orthoester intermediate was suggested by Fischer in the original publication on acyl migration. 301 Further, according to Casinovi et al, 304 the negative charge on the deprotonated hydroxy group would be stabilized by acceptance of a hydrogen bond from an adjacent hydroxy group, or for an O2 alkoxide, by the electron-withdrawing effect of the anomeric carbon.…”

Section: Mechanism Of Ester Migration In Polyolsmentioning

confidence: 99%

Mechanisms of Stereodirecting Participation and Ester Migration from Near and Far in Glycosylation and Related Reactions

et al. 2020

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This review is the counterpart of a 2018 Chemical Reviews article that examined the mechanisms of chemical glycosylation in the absence of stereodirecting participation. Attention is now turned to a critical review of the evidence in support of stereodirecting participation in glycosylation reactions by esters from either the vicinal or more remote positions. As participation by esters is often accompanied by ester migration, the mechanism(s) of migration are also reviewed. Esters are central to the entire review, which accordingly opens with an overview of their structure and their influence on the conformations of six-membered rings. Next the structure and relative energetics of dioxacarbeniun ions are covered with emphasis on the influence of ring size. The existing kinetic evidence for participation is then presented followed an overview of the various intermediates either isolated or characterized spectroscopically. The evidence supporting participation from remote or distal positions is critically examined and alternative hypotheses for the stereodirecting effect of such esters is presented. The mechanisms of ester migration are first examined from the perspective of glycosylation reactions, and then more broadly in the context of partially acylated polyols.

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Section: Mechanism Of Ester Migration In Polyolsmentioning

confidence: 99%

Mechanisms of Stereodirecting Participation and Ester Migration from Near and Far in Glycosylation and Related Reactions

et al. 2020

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show abstract

“…A mixture of methyl 6- O -trityl-α- d -glucopyranoside ( 40 ) (25 mg, 0.057 mmol), 1 (0.39 mg, 0.001 mmol) and acetic anhydride (6.3 μL, 0.063 mmol) was stirred in CHCl 3 (1 mL) for 45 min and worked-up as given in the general procedure B. Compound 41 73 was secured after column chromatography (SiO 2 ) (eluant: n -hexane–EtOAc 3 : 2), as a colorless gum (16.9 mg, 62%). 1 H NMR (400 MHz, CDCl 3 ) δ 7.46–7.44 (m, 6 H), 7.33–7.29 (m, 6 H), 7.26–7.23 (m, 3 H), 5.05 (t, J = 9.4 Hz, 1 H), 4.78 (d, J = 4 Hz, 1 H), 3.71–3.66 (m, 1 H), 3.61 (t, J = 9.2 Hz, 2 H), 3.44 (s, 3 H), 3.41–3.39 (m, 2 H), 2.15 (s, 3 H).…”

Section: Methodsmentioning

confidence: 99%

“…A mixture of methyl 6-O-trityl-α-D-glucopyranoside (40) (25 mg, 0.057 mmol), 1 (0.39 mg, 0.001 mmol) and acetic anhydride (6.3 µL, 0.063 mmol) was stirred in CHCl 3 (1 mL) for 45 min and worked-up as given in the general procedure B. Compound 41 73 was secured after column chromatography (SiO 2 ) (eluant: n-hexane-EtOAc 3 : 2), as a colorless gum (16.9 mg, 62%). 1 H NMR (400 MHz, CDCl 3 ) δ 7.…”

Section: Papermentioning

confidence: 99%