Unprecedented in Situ Oxidative Ring Cleavage of Isoxazolidines: Diastereoselective Transformation of Nitronic Acids and Derivatives into 3-Hydroxymethyl 4-Nitro Tetrahydrofurans and Pyrrolidines

Nitronic acids undergo an intramolecular 1,3-dipolar cycloaddition to unactivated double bonds, and the resulting isoxazolidines spontaneously evolve by an unprecedented in situ oxidative ring cleavage. The extension of this transformation to silyl nitronates results in a general diastereoselective construction of hydroxymethyl nitro functionalized tetrahydro-furans and -pyrrolidine having up to four consecutive stereogenic centers.