Synthesis of Chiral 10, 11 and 12-Membered Nitrogen and Oxygen Heterocycles by Intramolecular Nitrile Oxide Cycloaddition of Tethered N- and O-Allyl Carbohydrate Derivatives

Phthalate tethered strategy: carbohydrate nitrile oxide cycloaddition to 12–15 member chiral macrocycles with alkenyl chain length controlled orientation of bridged isoxazolines

The highly selective synthesis of phthalate templated bridged sugar-based isoxazoline macrocyclic lactones is demonstrated through INOC with alkene.

Solvent and catalyst free route to 3-indolyl glycoconjugates: synthesis of sugar tethered isoxazolines and isoxazoles from 3-indolyl nitroalkanes

An expedient, solvent and catalyst free strategy for the synthesis of sugar based bis(indolyl)methanes and indolyl nitroalkanes has been developed. Further, the nitroalkanes were converted to novel isoxazolines and isoxazoles by nitrile oxides cycloaddition.

Intramolecular Nitrile Oxide−Alkene Cycloaddition of Sugar Derivatives with Unmasked Hydroxyl Group(s)

[reaction: see text] Intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar derivatives with one to four free hydroxyl group(s) is reported. The INOC reaction, using chloramine-T, in the presence of silica gel, to generate nitrile oxides from oximes, proceeded smoothly to afford five- or six-membered carbocycles in good to excellent yields. This new methodology alleviates protection/deprotection steps and makes the synthetic route shorter and more efficient.

Synthesis and Intramolecular Nitrile Oxide Cycloaddition of 3,5‘-Ether-Linked Pseudooligosaccharide Derivatives: An Approach to Chiral Macrooxacycles

3,5'-ether-linked pseudooligopentose derivatives were synthesized for the first time from readily available carbohydrate precursors. The 1,2-isopropylidene-protected ether-linked oligopentoses are potentially important as precursors of novel RNA analogues. Intramolecular cycloaddition of the nitrile oxides prepared from these derivatives led to the diastereoselective formation of chiral isoxazolines fused to 10-16-membered oxacycles. The stereochemistry of some of these isoxazolines was established by X-ray diffraction and NOESY analysis.