The Participation of 3,3,3-Trichloro-1-nitroprop-1-ene in the [3 + 2] Cycloaddition Reaction with Selected Nitrile N-Oxides in the Light of the Experimental and MEDT Quantum Chemical Study

Abstract

The regioselective zw-type [3 + 2] cycloaddition (32CA) reactions of a series of aryl-substituted nitrile N-oxides (NOs) with trichloronitropropene (TNP) have been both experimentally and theoretically studied within the Molecular Electron Density Theory (MEDT). Zwitterionic NOs behave as moderate nucleophiles while TNP acts as a very strong electrophile in these polar 32CA reactions of forward electron density flux, which present moderate activation Gibbs free energies of 22.8–25.6 kcal·mol−1 and an exergonic character of 28.4 kcal·mol−1 that makes them irreversible and kinetically controlled. The most favorable reaction is that involving the most nucleophilic MeO-substituted NO. Despite Parr functions correctly predicting the experimental regioselectivity with the most favorable O-CCCl3 interaction, these reactions follow a two-stage one-step mechanism in which formation of the O-C(CCl3) bond takes place once the C-C(NO2) bond is already formed. The present MEDT concludes that the reactivity differences in the series of NOs come from their different nucleophilic activation and polar character of the reactions, rather than any mechanistic feature.

The First Examples of [3+2] Cycloadditions with the Participation of (E)-3,3,3-Tribromo-1-Nitroprop-1-Ene

“…So, TMH substituted conjugated nitroalkenes attract the attention of various research centers. In particular, 3,3,3-trichloro-1-nitroprop-1-ene was recently intensively tested as a component of different type cycloadditions involving diazocompounds [ 8 , 9 ], nitrile N -oxides [ 10 ], and especially nitrones [ 11 , 12 , 13 , 14 ]. Regarding 3,3,3-trifluor-1-nitroprop-1-ene, many interesting scientific works are also available at the present time [ 4 , 5 , 6 , 15 , 16 ].…”

On the Mechanism of the Synthesis of Nitrofunctionalised Δ2-Pyrazolines via [3+2] Cycloaddition Reactions between α-EWG-Activated Nitroethenes and Nitrylimine TAC Systems

“…The regioselectivity of polar processes of non-symmetric reagents can be specified through interaction between the most electrophilic center of the electrophile and the most nucleophilic ones of the nucleophile. For this purpose, electrophilic P k + and nucleophilic P k − Parr functions, derived from the changes of spin electron density reached via the GEDT process from the nucleophile to the electrophile, can be used as a powerful tool in the study of the local reactivity [42][43][44]. According to the nucleophilic P k − Parr functions of nitrylimine components 1a,c,e and the electrophilic P k + Parr functions of nitroethanes 2a-c in order to characterize the most nucleophilic and electrophilic centers of the species involved in this polar 32CA reaction were analyzed (Figure 1).…”

Polar [3+2] cycloaddition between N-methyl azomethine ylide and trans-3,3,3-trichloro-1-nitroprop-1-ene

“…As the model compound from this group we selected the trans-3,3,3-trichloro-1-nitroprop-1ene (2), which reactivity was recently tested by us in several different-type cycloaddition reactions [7][8][9][10].…”