合成路线1

Total synthesis: Reaction of ethyl acetopyruvate (I) with triethyl orthoformate gives compound (II), which is then treated with cyanoacetamide to yield 3-cyano-4-methyl-6-(carbethoxy)-2(1H)-pyridone (III). The reaction of (III) with methyl acrylate (A) gives compound (IV), which is sequentially submitted to decarboxylation, ketalization and treatment with diethylcarbonate, giving the functionalized tetrahydroindolizine (V). Ethylation of (V) followed by reduction in the presence of acetic anhydride gives the amide (VI), which is reacted with sodium nitrite, refluxed in CCl4, hydrolyzed and acidified to give the tricyclic compound (VII). The DIBAL reduction of (VII) and subsequent elimination of the hydroxyl group gives the cyclic enol ether (VIII). Asymmetric dihydroxylation of compound (VIII) with (DHQD)2PHAL, K2OsO4 and K3Fe(CN)6 in t-BuOH gives the diol (IX). The oxidation and deketalization of compound (IX) gives (S)-hydroxylactone (X). Finally, Friedlander condensation of the lactone (X) with 3-[N-isopropyl-N-(carbobenzyloxy)amino]-1-(2-aminophenyl)propan-1-one (B) followed by deprotection gives CKD-602.