Access to d- and l-Psicose Derivatives via Hydroxy Methylation of Ribono Lactone

Michael R Imrich,Thomas Ziegler

doi:10.3390/m1096

Abstract

2,3,5-Tri-O-benzyl- and 2,3,5-tri-O-methyl-d-ribono-γ-lactone were converted with (methoxyethoxymethoxy)methyl and benzyloxy tributylstannane into the corresponding protected d-psicoses as mixtures of anomers in 31%–72% yield. Treatment of 2,3,5-tri-O-methyl-l-ribono-γ-lactone with benzyloxy tributylstannane afforded the corresponding l-psicose derivative as an anomeric mixture in 72% yield. Both methylated psicoses were further converted into 1,2-O-isopropylidene-3,4,6-tri-O-methyl-d- and l-psicofuranosides, the respective α- and β-anomers of which could be separated and characterized.

Highlights

A few ketoses occur in nature nature in in significant significant amounts
Other ketoses like psicose (Figure 1) are rare carbohydrates which cannot be isolated in considerable amounts from carbohydrates sources
Synthesized either byby isomerization of the corresponding aldoses in low low yields or multi-step by multi-step syntheses involving different protectionand anddeprotection deprotectionsteps steps or or by yields or by syntheses involving different protection methods [2,3,4,5,6,7,8] resulting in a high price for these ketoses

Summary

Introduction d-Fructose

A few ketoses occur in nature nature in in significant significant amounts. amounts. Other ketoses like psicose (Figure 1) are rare carbohydrates which cannot be isolated in considerable amounts from carbohydrates sources. Theycan canbebe synthesized either isomerization of the corresponding aldoses in natural sources. As part of an ongoing research enzymatic methods project about the synthesis of carbohydrate derived catalysts for asymmetric syntheses [9,10,11,12] we required considerable amounts of dD- and l-psicofuranose. We chose as the starting both enantiomers of this sugar are commercially available atavailable decent costs [13] and the stereocenters because both enantiomers of this sugar are commercially at decent costs [13] and the possess the same configuration as psicose.

Results and Discussion the cheap cheap d-enantiomer and applied applied

Hydroxy methylation

Synthesis of methylated

H14 O5 Na

Conclusions