Ring Expansions of Photoadducts. Potential Applications in the Synthesis of Triquinane and Taxane Skeletons

Article abstract of DOI:10.1021/jo00269a012

Photoadditions of enones 4 or 18 with cyclopentene gave in good yield adducts 5/6 or 20/21, respectively, with the anti isomers predominating by a ratio of ca. 9:1.These adducts were converted to hydroxy ketones 9 or 24 by the following sequence: ketalization, LiAlH4 reduction, and hydrolysis.The alcohol function in these ketones was converted to a good leaving group, and the resultant derivatives were solvolyzed to give ring-expanded products 12 or 28 as well as bridged products 13-14 or 29-32, respectively.The sequence starting with the enone 18 has potentialapplications in the synthesis of the triquinane and the taxol carbon skeletons.