Ring Expansion of Donor–Acceptor Cyclopropane via Substituent Controlled Selective N-Transfer of Oxaziridine: Synthetic and Mechanistic Insights

Abstract

A distinctive N-substituent controlled electrophilic N-transfer of oxaziridines with donor-acceptor cyclopropanes in the presence of MgI is reported. Contrary to earlier reports, the oxaziridine having bulkier N-substituents can also give N-transferred product instead of the O-transferred one. Interestingly, the oxaziridines having α-H containing N-substituents lead to the pyrrolidine derivatives through [3 + 2] cycloaddition. A mechanistic reasoning for this divergent reactivity is depicted by density functional theory calculations and validated through energy decomposition analysis.

An Assessment of Electrophilic N‐Transfer of Oxaziridine with Different 2‐, 3‐, and 4‐Carbon Donor–Acceptor Substrates to Furnish Diverse N‐Containing Heterocycles in a Single Step

“…In our previous report, we have shown the N ‐substituent controlled dual reactivity of oxaziridine to donor–acceptor cyclopropane (DAC) for the one‐step access to valuable azetidine and pyrrolidine molecules (Scheme , A). It is noteworthy that even with the bulky N ‐substituent also we could able to get the corresponding N ‐transferred adduct in good yield. Indeed, the N ‐sulfonyl oxaziridines that were most commonly used as the O ‐transfer agent also followed the nonconventional and selective route of N ‐transfer reaction in the presence of magnesium iodide.…”

Donor–Acceptor Cyclopropanes as an Expedient Building Block Towards the Construction of Nitrogen‐Containing Molecules: An Update

“…Oxaziridines containing bulkier nitrogen substituents like tosyl, bosyl, and the tert ‐butyl group gave N‐transferred products instead of O‐transferred ones and afforded the respective azetidines 179 with good yields. Interestingly, the oxaziridines with α ‐H containing nitrogen substituents like methyl, isopropyl, methylbenzyl groups led to the formation of pyrrolidine derivatives 180 through [3+2] cycloaddition reaction between DACs 3 and in situ generated imines from the oxaziridines (Scheme ) …”

Me3SiBr/InCl3 catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

“…All the geometries including reactants, intermediates, transition states, and products were obtained at ωB97XD/def2‐SVP theory level . ωB97XD is range‐separated functional, which can obtain satisfactory accuracy for thermochemistry, kinetics, and noncovalent interactions and be used for reaction mechanism research with def2‐SVP basis set . The calculation used solvent model SMD, and hexane was taken as the solvent .…”

“…[29][30][31] ωB97XD is range-separated functional, which can obtain satisfactory accuracy for thermochemistry, kinetics, and noncovalent interactions and be used for reaction mechanism research [32][33][34][35][36] with def2-SVP basis set. [37][38][39] The calculation used solvent model SMD, [40][41][42] and hexane was taken as the solvent. [4] The free energy in the energy profile was corrected with single point energy at SMD-ωB97XD/def2-TZVP level.…”