A novel and short synthesis of (1,4/2)-cyclohex-5-ene-triol and its conversion to (+/-)-proto-quercitol

(1,4/2)-cyclohex-5-ene-triol was synthesized starting from cyclohexa-1,4-diene with two different approaches. Photooxygenation of cyclohexa-1,4-diene and epoxy-cyclohexene afforded anti-2,3-dioxabicyclo2.2.2]oct-7-en-5-yl hydroperoxide and anti-7-oxabicyclo4.1.0]hept-4-en-3-yl hydroperoxide, respectively. Hydroperoxy endoperoxide was reduced with aqueous sodium bisulfite; hydroperoxy-epoxide with dimethylsulfide-titanium tetraisopropoxide to give 7-oxabicyclo4.1.0]hept-4-en-3-ol. Acidic hydrolysis of the epoxy-alcohol gave the (1,4/2)-cyclohex-3-ene-triol. Oxidation of the double bond with KMnO4 resulted in the formation of (+/-)-proto-quercitol.