合成路线1

The reaction of the spiro compound (I) with CDI in refluxing dichloroethane gives the cyclic carbonate (II), which is condensed with the benzopyranone (III) by means of DEAD and PPH3 in DMF, yielding the adduct (IV). Elimination of the diphenylmethyl protecting group by hydrogenation with H2 over Pd/C in THF affords compound (V), which is acylated with acetic anhydride to provide the acetyl derivative (VI). The reaction of (VI) with O-(2-propynyl)hydroxylamine (VII) by means of LiClO4 gives the propargyloxycarbamate (VIII) as a mixture of regioisomers that are separated by chromatography. The opening of the carbonate ring of (VII) is accompanied by the formation of the corresponding oxime at the acetyl group of the benzopyran. This oxime is easily exchanged for methoxy by reaction with an excess of O-methoxyhydroxylamine and K-OAc in ethanol to give rise to the target compound.