Synthesis of paclitaxel C_(13) side chain

Aim:To synthesize paclitaxel C_(13) side chain.Methods:Epoxycinnammic acid(2) prepared from cinnammic acid(1) was resolved by R-α-phenylethylamine to give α-epoxycinnammic acid R-α-phenylethylamine salt(3).Compound 4,potassium salt of 3 reacting with sodium azide and acidified with hydrochloric acid to give azidoacid (5),methylester(6),which was prepared from compound 5 and HCl/MeOH,was reduced with Zn/NH_4Cl,the in situ formed amine(7) benzoylated with benzoic chloride to furnish 2S-hydroxyl-3S-N-benzoylaminophenylpropanoic acid methyl ester (8).Compound 8 was treated with mesylsulfonyl chloride in pyridine to give the title compound(4S-trans)-4,5-dihydro-2,4-diphenyl-5-oxazolecarboxylic acid methyl ester(9).Results:The synthesis of paclitaxel C_(13) side chain from cinnammic acid(1) was reported for the first time.Conclusion:The process for the synthesis of paclitaxel C_(13) side chain from cinnammic acid has the advantages of readily available starting materials,mild reaction conditions,being economical and easily scaled up.