Shenzhen Grubbs Institute, Department of Chemistry, Guangming Advanced Research Institute, Southern University of Science and Technology, Shenzhen 518055, China.
Shenzhen Bay Laboratory, Shenzhen 518132, China.
J Am Chem Soc. 2023 May 24;145(20):10998-11004. doi: 10.1021/jacs.3c03755. Epub 2023 May 11.
The first total synthesis of (±)- and (-)-daphnillonin B, a daphnicyclidin-type alkaloid with a new [7-6-5-7-5-5] A/B/C/D/E/F hexacyclic core, has been achieved. The [6-5-7] B/C/D ring system was efficiently and diastereoselectively constructed via a mild type I intramolecular [5+2] cycloaddition, followed by a Grubbs II catalyst-catalyzed radical cyclization. The [5-5] fused E/F ring system was synthesized via a diastereoselective intramolecular Pauson-Khand reaction. Notably, the synthetically challenging [7-6-5-7-5-5] hexacyclic core was reassembled by a unique Wagner-Meerwein-type rearrangement from the [6-6-5-7-5-5] hexacyclic framework found in calyciphylline A-type alkaloids.
（±）-和（-）-daphnillonin B 的全合成，一种 daphnicyclidin 型生物碱，具有新型 [7-6-5-7-5-5] A/B/C/D/E/F 六元环核心，已经实现。[6-5-7] B/C/D 环系通过温和的 I 型分子内[5+2]环加成，随后进行 Grubbs II 催化剂催化的自由基环化，高效且立体选择性地构建。[5-5]稠合的 E/F 环系通过立体选择性的分子内 Pauson-Khand 反应合成。值得注意的是，通过 calyciphylline A 型生物碱中发现的 [6-6-5-7-5-5] 六元环骨架的独特 Wagner-Meerwein 型重排，重新组装了具有挑战性的[7-6-5-7-5-5]六元环核心。
