A DFT Mechanistic Study of the Regio-, Chemo-, and Stereo- Selectivities of the (3 + 2) Cycloaddition of Diarylnitrone Derivatives with 1-(4-Nitrophenyl)-5H-Pyrrolin-2-One

Table 4

Activation and reaction energies corresponding to transition states and products for the 32CA reaction of A2 (X=H, CH3, and COOEt) and A1 (R=H) at the M06/6-311G (d, ) level of the theory in the gas phase for path A. All energies are in kcal/mol.

Substituents	TS1A-EXO	TS2A-ENDO	TS3A-EXO	TS4A-ENDO	P1A-EXO	P2A-ENDO	P3A-EXO	P4A-ENDO
Ph-NO2	4.5	10.6	9.6	7.6	−23.4	−20.4	−19.7	−20.3
H	8.6	11.5	13.2	11.7	−24.2	−21.8	−20.7	−21.6
CH3	7.4	11.4	11.5	9.8	−25.2	−22.4	−21.2	−22.3
COOEt	4.4	11.0	9.8	8.5	−24.9	−20.2	−19.3	−20.0