Synthesis of chiral pyranocyclohexane, oxepanocyclohexane, and furylpyran and -oxepane systems by the application of intramolecular nitrone and nitrile oxide cycloaddition of carbohydrate derivatives

Recent advances in the application of the Oppolzer camphorsultam as a chiral auxiliary

“…An efficient method for the stereocontrolled syntheses of 4,5-dihydroisoxazoles, 74 offering wide applications for the preparation of various pharmaceuticals 75 and natural products, 76 is the asymmetric 1,3-dipolar cycloaddition of nitrile oxides. The intermolecular diastereoselective cycloadditions of achiral nitrile oxides to optically active dipolarophiles, 77 (2R)-bornane-10,2-sultam to cycloalkenes was also achieved to construct the corresponding 2-isoxazoline in both moderate yields and diastereoselectivities.…”

1,3-Dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes

“…Chiral pyranobenzene-and oxepanobenzene-derived, and furylpyran and oxepane systems have also been accessed by the application of intramolecular nitrone and nitrile oxide cycloaddition reactions of carbohydrate derivatives. 38 Such strategies have proved of use for accessing the skeletal frameworks of natural products such as forskolin, 39 sipophenol A 40 and lasalocid A. 41 Studies have also been reported concerning the synthesis of various inositols and pseudo-sugars using intramolecular aldonitrone cycloaddition reactions of alkenyl nitrones derived from O-allylated sugar based aldehydes.…”

Nitro and related compounds

“…The nitrile oxide is prepared in situ by the action of Chloramine T on the oxime 34 with the subsequent cycloaddition proceeding in an 84% overall yield (Scheme 14). 74 2-Isoxazolines and oxazoles possessing phosphonate groups can be prepared by the 1,3-dipolar cycloaddition reaction of nitrile oxides with unsaturated phosphonates in 67-88% yields. 75 The oxidative action of manganese() oxide on aldoximes generates nitrile oxides in situ at ambient temperature, which can themselves be trapped with dipolarophiles to form 2-oxazoles in 41-92% yields.…”