An investigation of the molecular mechanism, chemoselectivity and regioselectivity of cycloaddition reaction between acetonitrile N-Oxide and 2,5-dimethyl-2H-[1,2,3]diazaphosphole: a MEDT study
The [3+2] cycloaddition (32CA) reactions of acetonitrile N-oxide with 2,5-dimethyl-2H-[1,2,3]diazaphosphole has been studied using the Molecular Electron Density Theory (MEDT) through DFT calculations at the B3LYP/6-31G(d,p) computational level. Analysis of the relative free energies associated with the competitive ortho and meta reaction paths shows high chemo- and regioselectivity for this 32CA reaction in clear agreement with the experimental outcomes. The topological analysis of the electron localization function (ELF) of the selected points of the IRC associated with the formation of the P-C and C-O single bonds indicates a zwitterionic type structure. The 32CA reaction takes place through a two-stage one-step mechanism initialized with the formation of the P-C single bond.
KeywordsDiazaphosphole acetonitrile N-oxide MEDT chemoselectivity regioselectivity
Supplementary Information (SI)
ELF topological analysis of the P–C and C–O bond formation along with the 32CA reaction between 2,5-dimethyl-2H-[1,2,3]diazaphosphole 1 and acetonitrile N-oxide 2. Tables include B3LYP/6-31g(d,p) total and relative electronic energies, in the gas phase and in THF, and B3LYP/6-31G(d,p) thermodynamic data, computed at 25 °C and 1 atm in THF, for the stationary points involved in the 32CA reaction of 2,4-dimethyl-2H-phosphorus 1 with acetonitrile N-oxide 2. Supplementary information is available at www.ias.ac.in/chemsci.
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