First asymmetric enantioselective total synthesis of phenanthridine alkaloid, (S)-(+)-asiaticumine and its enantiomer.

• The enantioselective total synthesis of (+)-asiaticumine A has been accomplished. • The construction of phenanthridine framework by MW-assisted electrocyclization. • The synthesis of 1,2-dihydroxyethyl moiety by Sharpless asymmetric dihydroxylation. • Its absolute configuration was determined to be S by Mosher's method. In this study, the first asymmetric enantioselective total syntheses of (+)-asiaticumine A (2) and its enantiomer were accomplished through a seven-step sequence using the bond formation between the C4a and N5 positions of the phenanthridine framework based on the microwave-assisted electrocyclization of cyclohexenylbenzaldoxime methyl ether as an aza 6π-hexatriene system followed by the Sharpless asymmetric dihydroxylation as the key step. In addition, the absolute configuration of natural (+)- 2 was determined to be S by Mosher's method. [ABSTRACT FROM AUTHOR]