Concise Asymmetric Synthesis of Fully Substituted Isoxazoline-N-Oxide through Lewis Base Catalyzed Nitroalkene Activation



original image

Transforming isoxazoline-N-oxides: A concise asymmetric synthesis of isoxazoline-N-oxides is reported through secondary amine Lewis base catalyzed nitroalkene activation and sequential intermolecular condensation with aldehydes and ylides. Application of camphor-derived chiral sulfur ylides gave the enantiomeric-enriched isoxazoline-N-oxides in excellent yields and stereoselectivity. Simple transformations of isoxazoline-N-oxide led to the gram-scale synthesis of a (−)-clausenamide analogue in four steps, with excellent stereochemistry control (see scheme).