COMMUNICATIONS require a catalyst system for which azomethine ylide dissociation is completely suppressed. This may be attainable simply by judicious ligand design; however, it is possible that a fundamentally different metal-ligand system will be required. In this context, it is compelling to note the potential similarities between metal complexes of azomethine ylides and n-ally1 ligands, especially in light of the recent marked advances in asymmetric catalysis with n-ally1 complexes.~'71
Experimentul ProcedureRepresentative procedure for the aziridination of I : A solution of 1 (0.113 g, 0.625 mmol, 1.000 equiv), 4 a (0.031 g, 0.094 mmol, 0.150 equiv, Aldrich). and [CuPF,(CH,CN).,] [7] (0.023 g, 0.063 mmol, 0.100 equiv) in CH,CI, (2.50 mL) containing 4 A molecular sieves was stirred under nitrogen at room temperature for 10 min. Ethyl diazoacetate (2.50 mL. 0 . 2 5~ in CH,CI,, 0.625 mmol. 1.000 equiv) was added by syringe pump over 12.5 h. and the solution was allowed to stir 1 h after the addition was complete. The crude reaction mixture was filtered through a plug of basic alumina (Brockmann. Activity I), eluting with CH,C!,, and analyzed by GC and ' H N M R after addition of a known quantity of internal standard (acetophenone). Alternatively, the reaction mixture could be purified directly by chromatography on silica gel (gradient elution. hexanes -t 2% ethyl acetate in hexanes -4 % ethyl acetate in hexanes; R, (10% ethyl acetate in hexanes): 0.50 (cis-2).
(rruns-2).