Photochemical Transformations, 75. The Azo/Nitrene Route to cis,cis‐Trialkyltriaziridines, 21b) Photolysis of syn‐Azo Azides of Defined Proximity – Attempts for N3 → N3X Ring Enlargement

The as yet unknown route to triaziridines by the addition of nitrenes to the π side of the N=N bond is achieved intramolecularly by the photolysis (thermolysis) of syn-azo azide substrates with high proximity; the yields reflects the sterical (and possibly inductive) influences of the skeleton. The product composition is rather independent of the exciting light; intramolecular azo→azide energy transfer is assumed. The kinetic skeleton stabilization of the triaziridines permits the synthesis of 17 (18) by the thermolysis of 7 (8) at 200 o C with the product composition deviating only marginally from that of the photolysis. Attempts towards enlargement on the triaziridines to N 3 X rings (X=CHR, O, NR) lead exclusively to products of intramolecular fragmentation