Photochemical Transformations, 75. The Azo/Nitrene Route tocis,cis-Trialkyltriaziridines, 21b) Photolysis ofsyn-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 pi side of the N = N bond is achieved intramolecularly by the photolysis (thermolysis) of syn-azo azide substrates with high proximity; the yields reflect 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-degrees-C with the product composition deviating only marginally from that of the photolysis. Attempts towards enlargement of the triaziridines to N3X rings (X = CHR, O, NR) lead exclusively to products of intramolecular fragmentation.