The absolute configuration of the decipiene diterpenes has been determined by degradation to 4R-4-(2-methoxy-4-methylphenyl)-pentanoic acid. Photolysis of 1, 18-diacetoxy-13- oxodecipi-14-ene proceeds through a novel photochemical reaction, formally a [2+ 2] cycloreversion, to generate a key intermediate for the degradation.
