ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Triaziridines. Synthesis of cis-2,3-Diisopropyltriaziridine-1-carboxylic EstersIrradiation of the (Z)-azimines 1a, b in Et2O with a Hg high pressure lamp through Corex yielded (besides 30% of the previously described trans-triaziridines 3a, b) 15% of the new cis-triaziridines 4a, b. The same irradiation of the (E)-azimines 2a, b afforded only 15-18% of 3a, b but 20-23% 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 10-15% of the ‘triazones’ 5a, b, 11-20% of the carbamic esters 6a, b, and 5-10% 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.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19850680624
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