Single Diastereomers of Polyhydroxylated 9-Oxa-1-azabicyclo[4.2.1]nonanes from Intramolecular 1,3-Dipolar Cycloaddition of ω-Unsaturated Nitrones

Abstract

8-Benzyloxymethyl-3,4,5-tribenzoyloxy-9-oxa-1-azabicyclo[4.2.1]nonane has been prepared as the single diastereoisomer 8 from an intramolecular 1,3-dipolar cycloaddition involving 2-(benzyloxy)acetaldehyde and omega-unsaturated hydroxylamine 7 derived from methyl alpha-D-glucopyranoside. The analogous 8-methoxycarbonyl 9-oxa-1-azabicyclo[4.2.1]nonane was afforded in a similar manner, from methyl D-galactopyranoside and methyl glyoxylate, as a 3:1 mixture of diastereoisomers 15 and 16. When conducted in achiral ionic liquid 17 this ratio increased to 8:1, and in chiral ionic liquid 18, compound 15 was formed exclusively.

Methyl 2,3,6-tri-O-Benzoyl-4-O-(tert-butyldimethylsilyl)-β-d-galactopyranoside

“…Column chromatography, using a mixture of petroleum ether-EtOAc (2:1) as the mobile phase afforded 1.68 g (50%) of compound 3 as a white solid. 1 H-NMR spectroscopic data for the product was in agreement with data reported previously [14].…”

Recent Advances in the Synthesis and Application of Chiral Ionic Liquids

“…[61][62][63][64][65][66][67][68][69] The known salt (S)-3-ethyl-1-(1-hydroxypropan-2-yl)-1H-imidazol-3-ium hexafluorophosphate 70 was recently applied in an intramolecular 1,3-dipolar cycloaddition which led to the formation of a single diastereomer. 71 Recently, Lin and co-workers prepared a new class of ionic liquids using epoxides for the introduction of a hydroxy-bearing N-alkyl group ( Figure 5). 72 Two different synthetic methods were followed (Scheme 16).…”

Synthesis of 1,5-Functionalized 1,2,3-Triazoles Using Ionic Liquid/Iron(III) Chloride as an Efficient and Reusable Homogeneous Catalyst

“…ILs have recently received a good deal of attention since classical organic reactions, including cycloadditions reactions, can be performed in these media with great advantages (yield and selectivity) as compared to conventional conditions [26][27][28][29][30]. Ionic liquids are distinguished by the advantages pertaining to these solvents, such as no measurable vapor pressure, easy solvent recover/recycle, and high solubility of the Lewis acids in these solvents [31][32][33].…”