The preparation of 3-methyl-4-nitro-5-(2-alkylethenyl)isoxazoles

Asymmetric Phase Transfer Catalysed Michael Addition of γ-Butenolide and N-Boc-Pyrrolidone to 4-Nitro-5-styrylisoxazoles

Herein we report the addition of acidic γ-butenolide and N-Boc-pyrrolidone to 4-nitro-5-styrylisoxazoles, a popular class of cinnamic ester synthetic equivalent. The reactions proceeded under the catalysis of Cinchona-based phase-transfer catalysts. Functionalised γ-butenolides were obtained in good isolated yields and moderate enantioselectivity (up to 74% ee).

An improved procedure to prepare 3-methyl-4-nitroalkylenethylisoxazoles and their reaction under catalytic enantioselective Michael addition with nitromethane

A two-step preparation of 3-methyl-4-nitro-5-alkylethenyl isoxazoles is herein reported. These were reacted with nitromethane under phase-transfer catalysis to provide highly enantioenriched adducts (up to 93% ee).

Catalytic enantioselective addition of isocyanoacetate to 3-methyl-4-nitro-5-styrylisoxazoles under phase transfer catalysis conditions

The reaction between 3-methyl-4-nitro-5-styrylisoxazoles and ethyl isocyanoacetate proceeded under PTC to give enantioenriched monoadducts in high ee (up to 99%).