Application of Lithiation–Borylation to the Total Synthesis of (−)-Rakicidin F

Abstract

The stereochemistry of the lipophilic side chain of (+)-rakicidin F had not been determined until recently. Using our lithiation–borylation methodology (“assembly line synthesis”) we were able to efficiently prepare the all-syn isomer as well as the C-21 epimer of the side chain, and comparison with the natural product suggested that the natural product had all-syn stereochemistry. Completion of the total synthesis using a macrolactamization of the northern amide enabled us to confirm Wang and Chen’s stereochemical findings for the structure of (+)-rakicidin F.

Recent Progress on the Zweifel Olefination: An Update

“…Subsequent hydrogenation of the double bond using PtO 2 as the catalyst transformed the olefin motif into an ethyl group, which was preserved in the final product (Scheme 12 ). 17…”

Marine natural products

“…[68][69][70][71] Two structural revisions of bacterial MNPs were reported in 2022; the absolute congurations of the cyclic peptides ogipeptin A 237 and tumescenamide A 238 were corrected via total synthesis. 72,73 Other total syntheses of bacterial NPs included cyanogramides A and C, 74 (±)-nesteretal A, 75 lucentamycin A together with barmumycin, oxotomaymycin and oxoprothracarcin, 76 rakicidin F, 77,78 anthracimycin and anthracimycin B, 79 xiamycins C-F, 80 seongsanamide E, 81 salimabromide, 82 (+)-nocardioazine B, 83 the indolocarbazole alkaloid ZHD-0501, 84 (±)-spiroindimicins A, D, G and H, 85 bahamaolide A, 86 aqabamycin G, 87 and elmonin and pratenone A. 88 Reviews focused on marine bacterial NPs published during 2022 included publications on the biosynthesis of microbial terpenoids, 89 polyketides and non-ribosomal peptides, 90 ribosomal peptides, 91 and the anthracyclines.…”