The invention discloses a synthetic method of a Fuan mycin skeleton. The method adopts a compound of a formula 1 as a starting material, and a compound of a formula 3 is obtained by removing a 
silicon protection group in a two-step conversion manner by virtue of 
Sonogashira coupling reaction. The compound of formula 4 is also used as a starting 
raw material to obtain the compound of formula 6 by virtue of pinic oxidization and methyl esterification. The compound of formula 3 and the compound of formula 6 have the 
Sonogashira coupling reaction, a phenolic hydroxyl group is protected by a 
silicon group, methoxyl is selectively removed, an acetylenic bond is reduced, 6pai electrocyclization is carried out, the phenolic hydroxyl group is activated to have the secondary 
Sonogashira coupling reaction, the 
silicon-group protective group is removed, a 
Ullmann reaction is carried out, methyl protection, pinic oxidization and Fourier-krafz 
acylation are carried out, esters are hydrolyzed and condensated with 
amino acid, the acetylenic bond is hydrolyzed into 
ketone under the gold 
catalysis, thus obtaining Fuan mycin skeleton protected by pentamethoxyl, and synthesizing the Fuan mycin skeleton. The synthetic 
route is reasonable in design, raw materials are cheap and easy to get, the operation is simple and easy, a key reaction midbody is easy to modify, and the synthetic research of various polycyclic xanthenone natural products can be realized by utilizing the method.