A novel photoinduced intramolecular cycloaddition reaction of1-(o-methoxycarbonylmethoxyphenyl)-2-pentamethyldisilanyl ethyne

Walsucochins A and B with an Unprecedented Skeleton Isolated from Walsura cochinchinensis

“…215 nm (log ε 4.2) and one shoulder absorption at ca . 248 nm (log ε 3.9) of 1 were readily assignable to the α,β-unsaturated ketone group (Woodward's rule also gave 215 nm) and the phenylacetylene group, respectively. The first positive Cotton effect at 230 nm (Δε +8.61) and the second negative Cotton effect at 211 nm (Δε −7.37) arising from the exciton coupling of two different chromophores of the α,β-unsaturated ketone and the phenylacetylene moiety indicated a positive chirality for compound 1 .…”