合成路线1

This compound has been obtained by three related ways: 1) The condensation of (R)-tryptophan (I) with 2,2-dimethylpropanal (II) by means of NaOH in refluxing methanol yields the corresponding inmine (III), which is cyclized with ethyl chloroformate (IV) in dichloromethane to afford the oxazolidine (V). the regioselective methylation of (V) with methyl iodide and lithium diisopropylamide (LDA) in THF gives the new methylated oxazolidine (VI), which is finally hydrolyzed with refluxing 6N HCl. 2) Ring opening of oxazolidine (VI) with LiOH in methanol gives (R)-N-(ethoxycarbonyl)-alpha-methyltryptophan methyl ester (VII), which is hydrolyzed with 6N HCl as before. 3) Ring opening of oxazolidine (VI) with LiOH in methanol/water gives (R)-N-(ethoxycarbonyl)-alpha-methyltryptophan (VIII), which is hydrolyzed with 6N HCl as before.