| 1 | Synthesis of Clionastatins A and B through Enhancement of Chlorination and Oxidation Levels of Testosterone显示文摘A full account of semisyntheses of polychlorinated marine steroids clionastatins A and B is described.We have developed a unique two-stage chlorination-oxidation strategy that enabled concise and divergent semisyntheses of clionastatins A and B in 16 steps from inexpensive testosterone.Key transformations in chlorination stage include(a)conformationally controlled,stereospecific dichlorination through an unusualβ-chloronium intermediate to install the diequatorial C1,C2-dichloride;(b)C4-OH directed C19–H oxygenation followed by challenging neopentyl chlorination to install the C19–Cl.The high oxidation level was constructed through(a)the desaturation at C6–C7 through one-pot photochemical dibromination–reductive debromination;(b)regioselective anti-Markovnikov oxidation of the C6–C7 double bond by photoredox-metal dual catalysis to forge the B ring enone;(c)late-stage desaturation with SeO_(2)to introduce C8–C9 double bond.Wharton transposition was used to forge the D-ring enone,and thermodynamically driven epimerization secured the cis-fused C/D ring system.Furthermore,we also provided a 14-step approach to clionastatin A by optimizing the construction of the D-ring enone with a dehydration-oxidation sequence. | Hao Cui Yang Shen Ruifeng Wang Haoxiang Wei Xin Lei Yanyu Chen Pengfei Fu Haoxiang Wang Ruihao Bi Yandong Zhang | 2022 | Chinese Journal of Chemistry2022，40，23： | 0 |
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