Asymmetric Synthesis of Bicyclic Isoxazolines via Dearomative Cycloaddition of 4-Nitroisoxazoles with Zwitterionic π-Allyl Palladium Species.

Enantioselective dearomative cycloadditions of 4-nitroisoxazoles with vinylethylene carbonate () proceeded in the presence of Pd(dba) and ()-DTBM-SEGPHOS to give the corresponding bicyclic isoxazolines and in good to high yields with excellent enantioselectivities (≤99% ee). This synthetic approach could be applied to -tosyl vinyl aziridine and 2-methylidenetrimethylene carbonate. Further transformations of the resulting cycloadducts and yielded not only its derivatives and but also the novel tetracyclic skeleton .