Abstract: A substituted benzene derivative is prepared in a process, which includes reacting a furan derivative of formula (I): wherein R is an alkyl group, with an olefin of formula (II): R1—CH?CH—R2??(II) wherein R1 and R2 are the same or different and independently are selected from the group consisting of hydrogen, —CN, —CHO and —COOR3, wherein R3 is selected from hydrogen or an alkyl group, or R1 and R2 together form a —C(O)—O—(O)C— group, with the proviso that R1 and R2 are not both hydrogen, to produce a bicyclic ether; and dehydrating the bicyclic ether to obtain a benzene derivative. The benzene derivative thus obtained can suitably be converted to a benzene carboxylic acid compound by oxidation.