Total Synthesis of 8-epi-Javaberine A and Javaberine A
摘要:
The total synthesis of berberine alkaloid javaberine A was examined. The B/C ring of berberine was successfully constructed by sequential Bischler-Napieralski cyclization-reduction protocols, and final demethylation afforded both javaberine A and its epimer.
Total Synthesis of 8-epi-Javaberine A and Javaberine A
摘要:
The total synthesis of berberine alkaloid javaberine A was examined. The B/C ring of berberine was successfully constructed by sequential Bischler-Napieralski cyclization-reduction protocols, and final demethylation afforded both javaberine A and its epimer.
The tetrahydroprotoberberine framework of javaberine A was synthesized by repeated hydroamination of dienylamine as the key step. The selection of the reaction solvents and additives highly influenced the reaction pathway and stereoselectivity, and stepwise hydroamination with optimal reaction conditions effectively constructed the tetrahydroprotoberberine skeleton.
Diastereoselective synthesis of 8-benzyltetrahydroprotoberberines was examined. Although Stevens rearrangement of N-benzylxylopinine resulted in poor yield and diastereoselectivity, benzylation of tetracyclic iminium successfully gave H8-H14 trans-benzyltetrahydroprotoberberines with high stereoselectivity.
Total Synthesis of 8-epi-Javaberine A and Javaberine A
The total synthesis of berberine alkaloid javaberine A was examined. The B/C ring of berberine was successfully constructed by sequential Bischler-Napieralski cyclization-reduction protocols, and final demethylation afforded both javaberine A and its epimer.