Total synthesis of 1RS,4SR,5RS-4-(4,8-dimethyl)-5-hydroxy-7-nonen-1-yl)-4-methyl-3,8-dioxab icyclo[3.2.1]octane-1-acetic acid and related compounds

The process for the preparation of a compound of the formula

• which comprises reacting a compound of the formula ##STR87## with trimethylsilyl chloride to form an enol silylether of the formula ##STR88## reacting the enol silylether with a brominating agent to form a bromide of the formula ##STR89## reacting the compound formed with a peroxy acid to form an epoxide of the formula ##STR90## reacting the epoxide with periodic acid to form an aldehyde of the formula ##STR91## reacting the aldehyde with an oxidizing agent to form an acid of the formula ##STR92## reacting the acid formed with a peroxy acid to form a bromo hemiketal .gamma.-lactone of the formula ##STR93## reacting the bromo hemiketal .gamma.-lactone with a trialkyl orthoformate to form a mixture of the cis/trans-bromo ketal lactone of the formula ##STR94## cyclizing the cis bromo ketal lactone with a cyclizing agent to form a bicyclic ketal acid of the formula ##STR95## reacting the ketal acid with a first reducing agent to form an alcohol of the formula ##STR96## reacting the alcohol with methanesulfonyl chloride to form a mesylate of the formula ##STR97## reacting the mesylate with a compound of the formula ##STR98## to form a condensation product of the formula ##STR99## hydrolyzing and decarboxylating the carboxylic ester with a decarboxylating agent to form a ketone of the formula ##STR100## reducing the ketone with a second reducing agent to form an alcohol of the formula ##STR101## esterifying the alcohol with an esterifying agent to form an ester of the formula ##STR102## reacting the ketal with acid to form a hemiketal of the formula ##STR103## reacting the hemiketal with (carbethoxymethylene)triphenylphosphorane to form a compound of the formula ##STR104## isomerizing the 8-nonenyl ester with an isomerizing agent to form a 7-nonenyl ester of the formula ##STR105## and hydroxyzing the esters with a hydrolyzing agent, wherein R.sub.1 is hydrogen or a lower alkyl group having 1-5 carbon atoms, R.sub.2 is hydrogen or lower acyl having 2-5 carbon atoms, TMS is a trimethylsilyl group and MS is a methylsulfonyl group.