Lithiation-electrophilic trapping of N-sulfonyl-activated ethylene aziridines

Synthesis of Selenoaziridines: A Study on Stereochemical Outcomes of the Reaction of Aziridine Radicals and Anions Generated from Iodoaziridines

The synthesis of a new functional group in the form of selenyl-substituted aziridines is described. Selenoaziridines are stereoselectively prepared by functionalization of intact aziridine precursors involving radical and anionic intermediates. Radicals are generated from cis-N-Ts iodoaziridines by activation of the C-I bond using alkoxides as a source of single electrons. These form predominantly trans-substituted selenoaziridines dependent on the size of the diselenide. cis-Aziridinyllithiums generated by Li-I exchange also react with diselenides stereospecifically to form a range of cis-selenoaziridines. Proposals for the stereochemical outcome are presented.

rac-2-Phenyl-1-[(2,4,6-triiso-propyl-benzene)-sulfon-yl]aziridine

In the title compound, C23H31NO2S, the geometry of the triiso-propyl-phenyl group is slightly distorted, with elongated C-C bonds at the ipso-C atom, and an S atom which deviates from the benzene ring plane by 0.228 (2) Å. This distortion is caused by the bulky substituents and, in comparison, an unbent geometry is observed in N-toluene-sulfonyl-aziridine [Zhu et al. (2006 ▶). Acta Cryst. E62, o1507-o1508]. π-π inter-actions between adjacent benzene rings [centroid-centroid distance = 3.7928 (11) Å] and are observed.

Highly cis-selective synthesis of iodo-aziridines using diiodomethyllithium and in situ generated N-Boc-imines

The first preparation of iodoaziridines is described. The addition of diiodomethyllithium to N-Boc-imines affords these novel aziridines in high yields. The reaction proceeds in one-pot via a highly diastereoselective cyclisation of an amino gem-diiodide intermediate.

Palladium-catalyzed cross-coupling of aziridinylmetal species, generated by sulfinyl-magnesium exchange, with aryl bromides: reaction optimization, scope, and kinetic investigations

A series of novel, highly substituted N-PMP aziridines have been accessed in high yields by palladium-catalyzed cross-coupling of intact aziridines. The cross-coupling employed aryl bromides and tertiary organometallic aziridines, generated from sulfinylaziridines by sulfinyl-magnesium exchange and transmetalation to the aziridinylzinc with zinc chloride. A wide range of electron-rich and electron-poor aryl bromides were utilized to afford the functionalized aziridine products as single diastereoisomers with retention of configuration at the reacting center. Assessment of the reaction kinetics showed zero-order in both the aziridine species and the aryl bromide. This indicated that the rate-determining step was reductive elimination from the palladium(II) species bearing both the aziridine and aryl groups to form the hindered C-C bond. The intermediate aziridinylzinc species underwent a progressive, background degradation that led to a plateau in yield and afforded reduced yields in substrates with ortho-substituted aryl groups, which are less reactive due to the additional steric demands.