A short synthesis of naturally occurring and other analogues of plakinic acids that contain the 1,2-dioxolane group

Natural and unnatural analogues 4 of plakinic acids A, C and D have been prepared in three steps from alkan-2-ones by (i) LDA-induced condensation with ethyl 3-methylbut-2-enoate to give (2Z)-3,5-dimethylalka-2,4-dienoic acids 10, then (ii) isomerisation to the 2E-isomers 5 and finally (iii) peroxymercuriation with 30% hydrogen peroxide and reduction in situ with sodium borohydride.