Concise Asymmetric Syntheses of Streptazone A and Abikoviromycin**

Streptazone A and abikoviromycin are alkaloids that both feature an unusual arrangement of reactive functionalities within a compact tricyclic ring system. Here, we report a highly concise asymmetric synthesis of both natural products. The route first constructs another family member, streptazone B-1, using a rhodium-catalyzed distal selective allene-ynamide Pauson-Khand reaction. A regio- and enantioselective epoxidation under chiral phase-transfer catalytic conditions directly afforded streptazone A in 8 steps overall. In one additional step, a chemoselective, iridium-catalyzed reduction of the enaminone system then gave abikoviromycin. The reactivity of streptazone A towards a cysteine mimic, N-acetylcysteamine, was studied and revealed unanticipated transformations, including bis-thiol conjugation which may proceed via formation of a cyclopentadienone intermediate. With flexible access to these compounds, studies aimed to identify their direct biological targets are now possible.

Automated summary

The highly concise asymmetric synthesis of Streptazone A and abikoviromycin was reported in this study, which involved a series of catalytic reactions. Unexpected transformations of streptazone A towards a cysteine mimic, N-acetylcysteamine, were discovered, including the formation of bis-thiol conjugation. The research provides a flexible access to these compounds for further studies on their direct biological targets.