Investigating the regio-, stereo-, and enantio-selectivities of the [3+2] cycloaddition reaction of C, N-diarylnitrone derivatives with N-propadienylindole derivatives. A DFT study

Density functional theory (DFT) at the M06-2X/6-311 G(d,p) level of theory was used to investigate the [3+2] cycloaddition (32CA) reaction of N-propadienylindole derivatives and C, N-diarylnitrone derivatives leading to the formation of 5-and 4-methyleneisoxazolidine derivatives. The geometries of the corresponding transition structures reveal that the cycloaddition occurs via an asynchronous one-step mechanism. The formation of the 4-methyleneisoxazolidine isomer is preferential to that of the 5-methyleneisoxazolidine isomer. While electron -releasing groups (ERGs) on C, N-diarylnitrone promote the formation of the 5-methyleneisoxazolidine regioisomer, electron-withdrawing groups (EWGs) on C, N-diarylnitrone promote the formation of the 4-methyl-eneisoxazolidine. Both ERGs and EWGs on N-propadienylindole promote the formation of 4-methyleneisoxazo-lidine. For all cases, the reaction is kinetically controlled.