Synthese von cis-2,3-Diisopropyltriaziridin-1-carbonsaeureestern

Article abstract of DOI:10.1002/hlca.19850680624

Irradiation of the (Z)-azimines 1a,b in Et2O with a Hg high pressure lamp through Corex yielded (besides 30percent of the previously described trans-triaziridines 3a,b) 15percent of the new cis-triaziridines 4a,b.The same irradiation of the (E)-azimines 2a,b afforded only 15-18percent of 3a,b but 20-23percent of 4a,b.Thus, these azimine photocyclizations show some stereospecificity.The triaziridines 3a,b and 4a,b formed in this way were always accompanied by the same three types of by-products, namely 10-15percent of the 'triazones' 5a,b, 11-20percent of the carbamic esters 6a,b, and 5-10percent of the ether/nitrene insertion products 7a,b.The constitution and configuration of the new cis-triaziridines 4 followed from their spectral properties.Of particular interest are the symmetry properties of 4 derived from the 1H-, 13C-, and 15N-NMR spectra: The stereoisomers 3 and 4 differ only in that the isochronicity of the two constitutionally equivalent molecular halves is temperature dependent in 3 but independent in 4.Both triaziridines 3 and 4 exhibit the IR CO band at (for carbamates) remarkably high frequency.The results confirm that the alkyl-substituted N-atoms of triaziridines are pyramidally stable, that the corresponding acyl-substituted N-atoms (N(1)) are also pyramidal, but can invert more readily, and that rotation around the N(1), C(=O) bond is rapid.Thus, there can be only little amide-type delocalization between a triaziridine N-atom and an acyl substituent of the carbamate type attached to it.