Studies On The Synthesis Of Dl-Shikonin

Shikonin is the main composition of Lithospermum erythrohizon.It has many biologic activity in pharmacology,and it's also upstanding natural pigment.Shikonin has been applied in foods,cosmetics and printing industry generally and the amount of requirement is very enormous.In recent it has been at the verge of exhaustion because of mass collection.So many chemists engage in the research about the total synthesis of Shikonin.The dl-Shikonin was synthesized from 2,5-dimethoxy-benzaldehyde.In which the key intermediate 4-Hydroxy-5,8-dimethoxy-naphthalene-2-carbaldehyde was obtained by stobbe condensation,cyclization,reduction and oxidation.We contrasted several oxidation methods,In which the method of py-SO₃ oxidation not only had good yield but also had simple experiment condition.The dl-Shikonin was synthesized by a simple routine using corey reagent and 4-hydroxy-5,8-dimethoxy -naphthalene-2-carbaldehyde,Grignard reaction was employed to construct the side chain,and following demethylation of the intermediate gave the dl-shikonin.We explored a new route to get the dl-shikonin.In which the Grignard reaction was firstly employed to construct the side chain.It made the construction of side chain more convenience,but the total yelid of synthesis needs further improvement.