Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• of new reactions and strategies. In this work, a PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction of N-substituted cyclobutenone provided a facile approach to the direct construction of the ABCE tetracyclic framework of Aspidosperma alkaloids. DFT calculations showed

• involves a formal 1,3-C shift. Keywords: Aspidosperma alkaloids; [2 + 2]-cycloaddition/retro-Mannich reaction; DFT study; photoinduced electron transfer; Introduction Photochemical reactions, which enable the construction of topologically complex architectures from simple building blocks, have attracted

• tetracyclic indoline M, which was expected to serve as a common intermediate for the total synthesis of Aspidosperma alkaloids. These alkaloids constitute a large family of structurally complex compounds, which incorporate a pentacyclic ABCDE skeleton (Figure 1d, 1–8) [19][20][21][22][23]. However, the

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• (−)-terengganensine A (not shown) under the same divergent plan (Scheme 11). Divergent total synthesis of (−)-pseudocopsinine (149) and (−)-minovincinine (150) (Boger 2020) [74]: (−)-Pseudocopsinine (149) was isolated from Vinca erecta, with a structure related to the Aspidosperma alkaloids, containing an additional

• meroterpenoids (Lou). Divergent synthesis of crinipellins by radical-mediated Dowd–Backwith rearrangement (Xie and Ding). Divergent total synthesis of Galbulimima alkaloids (Shenvi). Divergent synthesis of eburnane alkaloids (Qin). Divergent synthesis of Aspidosperma alkaloids (Boger). Photoredox based synthesis

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• synthesis. This formal synthesis shows the power of the enantioselective allylic alkylation to access formerly racemic constructs as single enantiomers; Danishefsky’s synthesis is now rendered enantioselective. D) Aspidospermine The aspidosperma alkaloids have garnered much attention as beautiful targets

• for the synthetic chemist. Most of the 250-plus compounds in this class share a pentacyclic core, from the clinical anticancer therapeutics vincristine and vinblastine to the simpler aspidospermidine [60]. To address the challenging synthetic features of the aspidosperma alkaloids, many clever