Photocleavage of the C–O bond of 9-phenanthrylmethyl ω-anilinoalkyl ethers via photo-induced intramolecular electron transfer

Abstract

Photoreactions of the title compounds {ArCH₂O[CH₂]_nNHPh: Ar = 9-phenanthryl}1 and 2(n= 4 and 5) gave ω-[o-(9-phenanthrylmethyl)anilino]alkan-1-ols 7 and 8 and ω-[spiro-(9′,10′-dihydrophenthrene-9′,2-indolin)-1-yl]alkan-1-ols 9 and 10, respectively, by the cleavage of C–O bond, while that of another title compound 3(n= 6) gave spiro-compounds 17 and 18 with 12- and 14-membered-rings, respectively, as main products. The photoreaction is proposed to proceed via photo-induced intramolecular election transfer from comparison of the reaction products with those in the photoreaction of ArCH₂O[CH₂]₃Ph 5 in the presence of N-methylaniline and acetic acid. The structures of spiro-compounds 17, 18, and the acetate of 9 were confirmed by X-ray crystal structure analysis.