The synthesis of guaiane type sesquiterpene lactones is important due to the biological activities associated with their complex structures. The synthetic plan starts with abundant monoterpenes isolated from Brazilian essential oils. Thus p-menth-l-ene was converted into 2-bromo-6-isopropyl-3-methyl-cyclohept-2-enone by cycloaddition with dibromocarbene, ring expansion using AgNO3 anf PCC oxidation. Chemoselective reduction with zinc/acetic acid and thermodinamic alkylation in α with 2,3- dichloropropene gave a 2-chloroallyl α,β-unsaturated ketone. Treatment with concentrated sulphuric acid effected hydrolysis and dehydration to a furan fused to a cycloheptene with an oxaguaiane structures.