| Popis: |
Novel photoreactions of 1- and 2-naphthols with ethylene promoted by aluminum halides are described. Irradiation of 2-naphthol (2a) with AlX 3 (X=Cl, Br) and ethylene in CH 2 Cl 2 gave the corresponding [2+2] cycloadduct 7a in good yields. The major side product was 2-ethyl-1-naphthol (8a). Of the Lewis acids and alkenes examined, only AlCl 3 and AlBr 3 effected the reaction and only ethylene gave satisfactory results, although allene can also be employed. Naphthols 2b-e having different electron-attracting substituents on C-6 afforded [2+2] adducts 7b-e in moderate to good yields, while the reactions of C-3-alkyl-substituted derivatives 8a and 15b were unsuccessful |
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