PM3 study of cyclization of α- and β- d-glucosyl azides into 1,2-cyclic carbamates

The reaction of azido sugars with triphenylphosphine and carbon dioxide leading to cyclic carbamates has been studied by means of PM3 semiempirical quantum chemical computations to elucidate the detailed mechanisms of chemical processes involved in this transformation. Our results clearly indicate t...

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Bibliographic Details
Published in:Journal of molecular structure. Theochem 1997-05, Vol.395, p.61-69
Main Authors: Friant-Michel, P., Marsura, A., Kovacs, J., Pintér, I., Rivail, J.-L.
Format: Article
Language:English
Subjects:
Amino sugars
Cyclic carbamates
Iminophosphoranes
PM3 study
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Summary:The reaction of azido sugars with triphenylphosphine and carbon dioxide leading to cyclic carbamates has been studied by means of PM3 semiempirical quantum chemical computations to elucidate the detailed mechanisms of chemical processes involved in this transformation. Our results clearly indicate that the mechanism involving an isocyanate intermediate is preferred for both α- and β-anomers. In addition, we find that, in the case of the α-anomer, steric hindrance prevents the occurrence of direct cyclization and requires the opening of the pyranose ring, in contrast to the case of the β-anomer. This result explains the poor yield and the occurrence of three isomeric cyclic carbamates when the reaction is performed on the α- anomer.
ISSN:0166-1280
1872-7999
DOI:10.1016/S0166-1280(97)00092-4