The first total syntheses of (±)-norphoebine, dehydrophoebine, oxophoebine, dehydrocrebanine, oxocrebanine and uthongine and their cytotoxicity against three human cancer cell lines

The first total syntheses of (±)-norphoebine, dehydrophoebine, oxophoebine, dehydrocrebanine, oxocrebanine and uthongine have been achieved. The crucial step involved the formation of ring C by a microwave-assisted direct biaryl coupling to produce the aporphine skeleton in high yields. The synthetic alkaloids were evaluated for their cytotoxicity against three human cancer cell lines MCF7, KB and NCI-H187. The results showed that uthongine was the best candidate of the series and it exhibited cytotoxicity against a human breast cancer MCF7 line with an IC₅₀ = 3.05 μM