13 14 (40%) communication we report on the SET photochemistry of, ß-unsaturated cyclohexenones with an-silyl tertiary amine donor. Earlier studies have shown that cation radicals derived from tertiary amines react via a-deprotonation and-CC bond cleavage, 3 and that¿ t-silylamine cation radicals undergo aC-Si bond rupture to produce-amino radicals. 2 Also, tertiary amines are known to serve as electron donors to the triplet states of conjugated cyclohexenones. This process produces aminecation radicals4 in pathways leading to adduct formation. 5 These observations suggest that,/3-unsaturated ketones 1 and tertiary a-silylamines 2 could participate in electron-transfer-in-duced photoaddition reactions as outlined in Scheme I. Pathways (3)(a) Davidson, RS; Steiner, P. RJ Chem. Soc., Perkin Trans. 1 1972, 1375.(b) Davidson, RS; Orton, S. P.. Chem. Soc., Chem. Commun. 1974, 209.(c) Inbar, S.; Linschitz, H.; Cohen, S. GJ Am. Chem. Soc. 1981, 103, 1048.(d) Shaefer, CG; Peters, K. S. Ibid. 1980, 102, 7566.(e) Manring, LE; Peters, K. S. Ibid. 1983, 105, 5708.(f) Manring, L. E.; Peters, K. S. Ibid. 1985, 107, 6452.(g) Lewis, F. D.; Zebrowski, BE; Correa, P. E. Ibid. 1984, 106, 187.(h) Lewis, F. D.; Correa, P. E. Ibid. 1984, 106, 194.(i) Hub, W,; Schneider, S.; Dorr, F.; Oxman, J. D.; Lewis, F. D. Ibid. 1984, 106, 708.