We report a unified total synthesis of five bufadienolides: bufalin (1), bufogenin B (2), bufotalin (3), vulgarobufotoxin (4), and 3-(N-succinyl argininyl) bufotalin (5). After the steroidal ABCD ring 8 was produced, the D ring was cross-coupled with a 2-pyrone moiety and stereoselectively epoxidized to generate 6. TMSOTf promoted a stereospecific 1,2-hydride shift from 6 to establish the β-oriented 2-pyrone of 19. Functional group manipulations from 19 furnished 1–5, which potently inhibited cancer cell growth.

中文翻译：

---

五种丁二烯内酯的统一全合成

我们报告了五个bufadienolides的统一总合成：bufalin（1），bufogenin B（2），bufotalin（3），vulgarobufotoxin（4）和3-（N-琥珀酰精氨酰基）bufotalin（5）。甾体ABCD环8产生后，D环与2-吡喃酮部分交叉偶联并立体选择性环氧化生成6。TMSOTf促进了立体定向的1,2-氢化物从6转变为19的β定向2-吡喃酮。从官能团操作19提供1 - 5，可有效抑制癌细胞的生长。