Regioselective Acylation of Octyl β-d-Glucopyranoside by Chiral 4-Pyrrolidinopyridine Analogues

Abstract

Chiral 4-pyrrolidinopyridine (PPY) analogues with dual functional side chains consisting of indole units have been prepared from trans-4-hydroxy-l-proline. Treatment of octyl β-d-glucopyranoside with isobutyric anhydride in the presence of the catalysts gave the 6-O-acylate as the major product via acylation of a primary hydroxyl group. On the other hand, the 4-O-acylate was obtained as the major product in 66% regioselectivity via acylation of the secondary hydroxyl group at C-4 on treatment of octyl β-d-glucopyranoside with isobutyric anhydride in the presence of a PPY catalyst. Use of isobutyryl chloride instead of isobutyric anhydride in the presence of the catalyst gave the 6-O-acylate in 87% regioselectivity.

Key words

regioselective acylation - nucleophilic catalyst - gluco­pyranoside - chiral pyrrolidinopyridine - organocatalyst

References

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Reversal in regioselectivity of acylation depending on the acylation agent was also reported by Kattnig and Albert, see reference 11.