Search

Concise syntheses of 9-methoxyellipticine, 3,4-dihydroellipticine (µ-alkaloid D), 1,2,3,4-tetrahydroellipticine, 2-methyl-1,2,3,4-tetrahydroellipticine, olivacine, 3,4-dihydroolivacine, (±)-guatambuine, and (±)-janetine were developed starting from hexatriene intermediates readily obtained by Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborates. The route enables the facile construction of pyrido[4,3- b]carbazoles by Cu-catalyzed 6π-electrocyclization and subsequent transformation of the pyridocarbazole intermediates into pyrido[4,3- b]carbazole alkaloids. [ABSTRACT FROM AUTHOR]

In this study, we achieved the total synthesis of carbazole alkaloid mukoenine A through a seven-step sequence involving the construction of a carbazole framework using the electrocyclization of a 6π-electron system including an allene intermediate as the key step. Subsequently, the synthesis of pyrano[3,2- a ]carbazole alkaloid girinimbine was achieved by the construction of the pyran ring via selenoetherification of the o-allylic phenol moiety of mukoenine A. [Display omitted] • The total synthesis of mukoenine A has been accomplished via a seven-step sequence. • Girinimbine was synthesized by the construction of the pyran ring via mukoenine A. • The carbazole framework was constructed by the allene-mediated electrocyclization. [ABSTRACT FROM AUTHOR]

• 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]