The title phosphate ester was prepared from N-acetylcolchinol (I). Treatment of (I) with di-tert-butyl diethylphosphoramidite in the presence of tetrazole provided the phosphite ester (II), which was subsequently oxidized to phosphate (III) by means of MCPBA. The tert-butyl phosphate ester of (III) was finally cleaved using trifluoroacetic acid.

The reaction of colchicin (I) with aq. HCl at 100 C gives the monodemethylated compound (II), which is treated with H2O2 at 60 C to yield the dibenzocycloheptene derivative (III). The condensation of (III) with N,N-diethylphosphoramidic acid di-tert-butyl ester (IV) by means of tetrazole affords the phosphoric acid triester (V), which is finally treated with MCPBA to provide the target phosphoric acid monoester.