Aziridine scaffolds for the detection and quantification of hydrogen-bonding interactions through transition-state stabilization

Linear bis-Coordinate Silver(I) and Iodine(I) Complexes with R3 R2 R1 N Tertiary Amines

Homoleptic [L-I-L]+ iodine(I) complexes (where L is a R3 R2 R1 N tertiary amine) were synthesized via the [L-Ag-L]+ → [L-I-L]+ cation exchange reaction. In solution, the amines form [R3 R2 R1 N-Ag-NR1 R2 R3 ]+ silver(I) complexes, which crystallize out from solution as the meso-[L-Ag-L]+ complexes, as characterized by X-ray crystallography. The subsequent [L-I-L]+ iodine(I) analogues were extremely reactive and could not be isolated in the solid state. Density functional theory (DFT) calculations were performed to study the Ag+ -N and I+ -N interaction energies in silver(I) and iodine(I) complexes, with the former ranging from -80 to -100 kJ mol-1 and latter from -260 to -279 kJ mol-1 . The X-ray crystal structures revealed Ag+ ⋅⋅⋅Cπ and Ag+ ⋅⋅⋅H-C short contacts between the silver(I) cation and flexible N-alkyl/N-aryl groups, which are the first of their kind in such precursor complexes.

Solvent-Controlled Regioselective Reaction of 2-Methyleneaziridines with Acrylic/Propargylic Acids: Synthesis of Carboxylate Aziridine/Acetone Esters

Herein, we report a convenient solvent-controlled regioselective esterification to access two types of carboxylate esters without any additive or non-green activation strategy. In this transformation, 2-methyleneaziridines served as an ester reagent, providing two alternative electrophilic carbon centers. Notably, this protocol is suitable for some structure-complicated clinical molecules with a carboxylic acid group, presenting remarkable application potential.

Nitrogen Stereodynamics and Complexation Phenomena as Key Factors in the Deprotonative Dynamic Resolution of Alkylideneaziridines: A Spectroscopic and Computational Study

The present work is aimed at shedding light on the origin of the stereoselectivity observed in the reactions of chiral heterosubstituted organolithiums, generated by lithiation of alkylideneaziridines. Factors such as the nitrogen inversion barrier, the stereochemistry at the nitrogen atom, the substitution pattern of the alkylideneaziridines, and the reaction conditions are taken into consideration. The interplay between nitrogen stereodynamics and complexation phenomena seems to be crucial in determining the stereochemical outcome of the lithiation/trapping sequence. The findings were rationalized by a synergistic use of NMR experiments, run on the lithiated intermediates, alongside computational data. It has been demonstrated that, in such systems, the stereochemistry-determining step is the deprotonation reaction, and a model based on a deprotonative dynamic resolution has been proposed. Such findings could find application in dynamic systems other than aziridines.

Study of boron-nitrogen dative bonds using azetidine inversion dynamics

A method for probing the strength of B-N dative bonds is reported. The activation parameters for nitrogen inversion in a series of azetidines tethered to boronate esters have been quantified by VT-NMR and the measured barriers correlated with data obtained by (11)B NMR, X-ray crystallography and MP2 calculations.