Abstract: It has been reported that buagarofuran(AF-5)as an anxiolytic drug. It possesses a structural feature including α-agarofuran and the n-butyl side chain. Recently, there is a new metabolite found in clinical study, which is hypothesized that the n-butyl side chain has been oxidized to carboxylic acid. In order to confirm its structure, the target compound was prepared from(4aR, 7R, 8aR)-8a-hydroxy-7-(2-hydroxypropan-2-yl)-4a-methyloctahydronaphthalen-2(1H)-one in a six-step reaction with an overall yield of 16. 7%. The structure is confirmed by NMR and MS.