“…In our previous reports we have shown that the nonselective [1-71 photochemical rearrangement of isoxazolines can be made selective by introducing a moiety, stabilizing the primary formed diradical. The photolysis of such products leads exclusively to heterocyclic enaminoaldehydes[8-11l.Measuring the quantum yields of the transformation of 4-R-substituted 8-phenyl-3,6,10-trioxa-9-azabicyclo- [5,3,0]-8-decenes 1 and 2 to 2-R-6-phenyl-7-formyl-~,4,5,8-tetrahydro-l,3-dioxa-S-azocines 3, where R was methyl and phenyl, we have found different @ values for eso derivatives '2b,cand endo derivatives 1 b , e. We now wish to report an investigation of this rare phenomenon on a greater series of derivatives 1 and 2.…”