The platinum-catalyzed tandem carboalkoxylation-Claisen rearrangement reaction of arylalkynes 1 beating an ortho-1,5-dihydro-3H-2,4-dioxepine group gave the corresponding tricyclic compounds 2 in good to allowable yields. For example, the reaction of 2-[2-(pent-1-ynyl)phenyl]-4,7-dihydro[1,3]dioxepin 1a, 2-[2-(oct-l-ynyl)phenyl]-4,7-dihydro[1,3]dioxepin 1c, and 2-[2-(phenylethynyl)phenyl]-4,7-dihydro[1,3]dioxepin 1d in the presence of 10 mol % Of PtCl2 and 40 mol % of beta-pinene in acetoftitrile at 100degreesC gave the corresponding tricyclic compounds 2a, 2c, and 2d in 69, 63, and 50% yields, respectively.