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 3

Activation and reaction energies corresponding to transition states and products for the 32CA reaction of 1-(4-nitrophenyl)-5H-pyrrolin-2-one A2 and A1 (meta, R=CH_3, OCH₃, (CH₃)₂N, Br, and NO₂) at the M06/6-311G (d, ) level of the theory in the gas phase for path A. All energies are in kcal/mol.

Meta
Substituents	TS1A-EXO	TS2A-ENDO	TS3A-EXO	TS4A-ENDO	P1A-EXO	P2A-ENDO	P3A-EXO	P4A-ENDO
H	4.5	10.6	9.6	7.6	−23.4	−20.4	−19.7	−20.3
ERGs
CH3	2.5	10.4	—	7.2	−24.8	−20.6	−20.2	−20.8
OCH3	3.6	10.3	5.2	6.3	−27.6	−21.4	−21.4	−22.0
(CH3)2N	−1.6	—	—	5.9	−28.4	−21.3	−21.9	−22.0
EAGs
Br	3.7	11.7	9.1	8.1	−25.3	−20.3	−19.4	−20.3
NO2	3.8	13.1	—	9.6	−24.2	−19.4	−17.6	−21.0