Total syntheses of smenothiazoles A and B

Abstract

Concise total syntheses of smenothiazoles A (1) and B (2), two distinguished vinyl chloride containing natural products isolated from the marine sponge S. aurea, have been developed. Silastannation, Stille reaction and a carefully controlled desilylchlorination were employed as key steps to construct unique polyketide acid fragments, and the optimized reaction conditions avoided migration of 2,5-diene to a 2,4-conjugated system. This report unambiguously confirmed the structures of both natural products.

Marine natural products

“…Compounds that have been synthesised include ancorinoside A, 487 diacarnoxide C, 488 and plakinidone C. 406 The structures of gracilioether I and mucosin have been disproven by synthesis but no alternatives have been proposed. 489,490 Jaspisin, isojaspisin and (Z)narain have been synthesised, 491 as have smenothiazoles A 406,492 and B. 492 The peptides ciliatamides A and D (revised to 1212 and 1213 respectively), 493 euryjanicin E, 494 reniochalistatin E, 495 and theonellapeptolide Id 496 and the diaryl ether tedarene A have all been synthesised.…”

“…489,490 Jaspisin, isojaspisin and (Z)narain have been synthesised, 491 as have smenothiazoles A 406,492 and B. 492 The peptides ciliatamides A and D (revised to 1212 and 1213 respectively), 493 euryjanicin E, 494 reniochalistatin E, 495 and theonellapeptolide Id 496 and the diaryl ether tedarene A have all been synthesised. 497 The absolute congurations of purpuroine A 1214 and nakirodin A 1215 have been revised following their synthesis, 498 while spiroleucettadine 499 and both madangamines C and E 500 have been made.…”

Marine natural products from sponges (Porifera) of the order Dictyoceratida (2013 to 2019); a promising source for drug discovery

“…In addition, this analogue was found to be able to block the cell cycle at the G 0 /G 1 phase. 15 Also from the same species (S. aurea), smenothiazoles A (17) & B (18) were isolated and showed potent cytotoxic activity at nanomolar concentrations on four different cell lines (Calu-1 and LC31 lung-cancer cells, A2780 ovarian cancer cells and MCF7 breast cancer cells). The tumor cells were treated for 48 h with different concentrations of the two compounds.…”

“…The optimized reaction conditions avoided the migration of 2,5-diene to a 2,4-conjugated system. 18 A new sesquiterpene (+)-5-epi-20-O-ethylsmenoquinone (19) was reported from S. aurea and S. cerebriformis. This compound exhibited inhibition tumor growth at 0.75 and 1.5 mM against 21 From the marine sponge Scalarispongia sp., four new scalarane sesterterpenoids were isolated.…”

“…Structures of compounds(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26).34962 | RSC Adv., 2020,10,[34959][34960][34961][34962][34963][34964][34965][34966][34967][34968][34969][34970][34971][34972][34973][34974][34975][34976] This journal is © The Royal Society of Chemistry 2020RSC Advances Review Open Access Article. Published on 21 September 2020.…”