Patent ID: 7018987

Claim:
A process for preparing a compound of Formula III, wherein: X represents a cis or trans alkenyl group represented by —(CH═CH) 1 —; one of —OR 1 or —OR 2 is O − Q + or —O—Q, and the other is hydroxyl, —O − Q + , or —O—Q; and Q is an alkali metal, an alkali earth metal, a transition metal, a heteroarylene, a heterocyclyl, a nucleoside, a nucleotide, an alkaloid, an amino-sugar, an amino-nitrile, or a nitrogen-containing antibiotic, the process comprising: a) contacting cis- or trans-combretastatin A-4 in a solvent with a di(arylmethyl)phosphite in the presence of a tetrahalomethane, a tertiary amine, and an acylation catalyst to form a protected phosphate ester of Formula I, wherein R 3 is an arylmethyl phosphate protecting group; and b) contacting the protected phosphate ester of Formula I with a trialkylhalo silane for a period of time sufficient to generate the phosphoric acid compound of Formula II and c) converting the phosphoric acid compound of Formula II into the compound of Formula III.