Photo-stimulated radical substitution

In order to determine the degree of competition between both processes, the photo -stimulated reaction of the radical probe 3-bromo-2-tetrahydropyranyl allyl ether (83) with Ph2P ions in liquid ammonia was studied. In this reaction both the substitution 84 (20% yield) and the cyclized 85 (69% yield) substitution products were formed (equation 67)54,151. 

---