Improved Synthesis of Liguzinediol

OBJECTIVE To identify and optimize the synthesis of liguzinediol. METHODS Ethyl acetoacetate was used as the starting material to obtain liguzinediol by nitration， Pd/C catalytic hydrogenation， condensation， dehydrogenation and sodium borohydride reduction. The reaction conditions were optimized. RESULTS When ethyl N-hydroxyiminoacetoacetate was prepared， the ratio of the raw material to sodium nitrite was 1∶ 1.4， the concentration of sodium nitrite aqueous solution was 16%. When diethyl 3，6-dimethyl-2，5-pyrazinedicarbonate was prepared， the reaction temperature was 30℃， 1 equivalent of trimethylamine， and the mass ratio of ethanol to the raw material was 8.8. When liguzinediol was prepared， the reaction solvents were THF and EtOH， 3 equivalents of sodium borohydride， 2 equivalents of anhydrous calcium chloride， and the reaction temperature was room temperature. The total product yield was 49.1%， while the purity was 99.91%. CONCLUSION The raw materials used in this route are cheap and easy to obtain， the reaction conditions are mild， the yield is increased to 49.1%， the product quality is controllable， and it is easy to enlarge the production.