Conversion of some azomethine ylides derived from 2-cyano-1-imidoaziridines into imines

Thermal rearrangement of 2,3-diaryl-1-phthalimidoaziridines

“…However, these results contradict the work of Person et al 21 who reported that the rearrangement of tri-and tetrasubstituted N-phthalimidoaziridines with at least one cyano group occurred quantitatively, even at room temperature in benzene or chloroform, to give a mixture of two isomeric imines with preferred migration of the phthalimide moiety to the carbon atom without the electron-withdrawing cyano group. 21 However, this information regarding the isomer ratios may be unreliable as these data 21 were opposite to those reported in a previous article 37 by the same authors (Table 2). In the case of aziridine 6b (vide infra), a yield of 100% was indicated for imine 8b whereas the characterization data were given for isomer 7b.…”

“…In the case of aziridine 6b (vide infra), a yield of 100% was indicated for imine 8b whereas the characterization data were given for isomer 7b. 21 In other cases, the NMR spectroscopic data were specified only for one of the two isomers.…”

“…21 2-Arylidenephenylacetonitriles 5a-c were prepared from substituted benzaldehydes and phenylacetonitrile using a literature procedure 38 and examined in the oxidative aminoaziridination reaction (Scheme 1). According to our standard procedure, using K 2 CO 3 as base, we achieved an improved yield of aziridine 6a (80% instead of 61% 21 ).…”

Intramolecular thermal transformations of N-phthalimidoaziridines: 1,3-dipolar cyclo-addition and rearrangements*

“…Cross peaks corresponding to NOE of the CH=N proton with the o-proton of the adjacent phenyl ring and with the NCHN proton, which is spatially-proximate in the (E)-isomer, are seen in the 1 H-1 H NOESY spectrum of compound 13a. We note that the formation of such imines has been observed previously upon heating several tri-and tetrasubstituted N-phthalimidoaziridines [9].…”

“…Opening of the three-membered ring to give the corresponding azomethine ylide evidently precedes this isomerization, while at least three mechanisms for shifting the phthalimide fragment to the adjacent carbon atom are theoretically possible: a concerted 1,2-shift and cleavage of the phthalimide group with subsequent recombination of the two species through an ion or radical pair. Person et al [9] presented experimental data serving as evidence against mechanisms involving participation of an ion or radical pair in their work on a similar isomerization of tri-and tetrasubstituted N-phthalimidoaziridines. These authors found no cross reactions, a high reaction rate in nonpolar solvents, and the lack of EPR signals.…”