Late‐Stage Bromination Enables the Synthesis of Rubrolides B, I, K, and O

Karak, Milandip; Acosta, Jaime A. M.; Barbosa, Luiz C. A.; Boukouvalas, John

doi:10.1002/ejoc.201600473

Cited by 17 publications

(14 citation statements)

References 55 publications

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“…We also tried to convert 8a directly into 10a by using several one‐pot aldol condensation procedures (e.g. TBSOTf/DIPEA/DBU/CH 2 Cl 2 , piperidine/CH 3 OH) that were successful in the synthesis of rubrolides and related natural products . However, none of them proved successful in isolating 10a from the resulting complex product mixtures.…”

Section: Resultscontrasting

confidence: 59%

Synthesis of new tetronamides displaying inhibitory activity against bloom‐forming cyanobacteria

Acosta

Karak

Barbosa

et al. 2019

Pest Management Science

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BACKGROUND: The increasing frequency and intensity of cyanobacterial blooms pose a serious threat to aquatic ecosystems. These blooms produce potent toxins that can contaminate drinking water and endanger the life of wild and domestic animals as well as humans. Consequently, the development of effective methods for their control is a matter of high priority. We have previously shown that some -benzylidenebutenolides, related to the rubrolide family of natural products, are capable of inhibiting the photosynthetic electron transport chain (Hill reaction), a target of commercial herbicides. Here we report the synthesis and biological properties of a new class of rubrolide-inspired molecules featuring a tetronamide motif.RESULTS: A total of 47 N-aryl tetronamides, including 38 aldol adducts, were prepared bearing phenyl, biphenyl, naphthyl, aliphatic and heteroaromatic groups. Some of the aldol adducts were dehydrated to the corresponding -benzylidenetetronamides, although satisfactory yields were obtained in only three cases (52-97%). None of the synthesized compounds were capable of blocking the Hill reaction. This notwithstanding, several aldol adducts equipped with a biphenyl substituent displayed excellent inhibitory activity against Synechococcus elongatus and other cyanobacterial strains (IC 50 = 1-5 M). Further, these tetronamides were found to be essentially inactive against eukaryotic microorganisms. CONCLUSION: Several newly synthesized biphenyl-containing tetronamides were shown to display potent and selective inhibitory activity against cyanobacteria. These compounds appear to exert their biological effects without interfering with the Hill reaction. As such, they represent novel leads in the search of environmentally benign agents for controlling cyanobacterial blooms.

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Section: Resultscontrasting

confidence: 59%

Synthesis of new tetronamides displaying inhibitory activity against bloom‐forming cyanobacteria

Acosta

Karak

Barbosa

et al. 2019

Pest Management Science

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“…Key steps in this approach included: a) a site‐selective SMCR b) a vinylogous aldol condensation and c) the final bromination. Pd‐catalyzed SMCR of 246 with the suitable boronic acids 37 or 41 gave 247a,b in yields of 76% and 51%, respectively compounds 247a and 247b are transformed into desired natural products in several steps, respectively (Scheme ) …”

Section: Coupling Of Sp2 Hybridized C–b Compoundsmentioning

confidence: 99%

“…Pd-catalyzed SMCR of 246 with the suitable boronic acids 37 or 41 gave 247a,b in yields of 76% and 51%, respectively compounds 247a and 247b are transformed into desired natural products in several steps, respectively (Scheme 38). [129] Brçnstrup [130] and Hoepfner [131] independently revealed the isolation of Nannocystin A 248 from the myxobacterium Nannocystis sp in 2015. Nannocystin A 248 has a 21-membered macrocycle that includes both peptide and polyketide domains.…”

Section: Hamigeran Bmentioning

confidence: 99%

Current Applications of Suzuki–Miyaura Coupling Reaction in The Total Synthesis of Natural Products: An update

Koshvandi

Heravi

Momeni

2018

Applied Organom Chemis

152

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Suzuki‐Miyaura Coupling Reaction (SMCR) has been extensively used in the total synthesis of natural products. We underscored these achievements in a report published in Tetrahedron up to 2012. Since then, there has been tremendous growth in this field and numerous articles have been published after 2012. In this review, we tried to go insight and highlight the current developments in the applications of SMCR as a key and strategic step (steps) in the total synthesis of biologically active natural products accomplished and reported from 2012 till date.

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“…A baixa reatividade desse aldeído já havia sido relatada durante a tentativa de síntese de rubrolídeos naturais. [40][41][42] Finalmente, o tratamento dos compostos 15a-k com BBr 3 resultou na obtenção dos derivados desmetilados 16a-i. Os rendimentos das reações de desmetilação dos análogos metoxilados 15a-c, 15e-g e 15i variaram de 64-86%.…”

Section: Sínteseunclassified

Inibição Do Crescimento De Microrganismos Patogênicos Induzida Por Butenolídeos Análogos Aos Cadiolídeos

Mairink

Barbosa

Maltha

et al. 2019

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INHIBITORY EFFECT ON GROWTH OF PATHOGENIC MICROORGANISMS INDUCED BY BUTENOLIDES RELATED TO CADIOLIDES. The increasing number of antibiotic resistant microorganisms requires the development of new drugs. In this context, natural cadiolides are promising leads as they present potent antimicrobial activity and low cytotoxicity. In this work we report the synthesis of 21 new cadiolide analogues. The synthesis involved a Diels−Alder cycloaddition/ cycloreversion reaction between an oxazole and different ynones, affording four intermediate butenolides (14a-d) in 61-81% yield. These intermediates were subjected to a vinylogous Knoevenagel condensation, followed by demethylation of the methoxylated compounds, affording all 21 analogues in good yields. The antibiotic activity of all compounds was evaluated against a panel of five microorganisms. The bioassays on the microbial growth showed that the cadiolides are more active for Gram-positive than Gram-negative bacteria, and have low activity against the fungus C. albicans. The most active compounds (14b, 15b, 15c and 16e) were effective against S. aureus showing IC 50 in the range of 1.8-6.0 µg mL-1. The results also indicated that the nature and position of substituent groups on the aromatic moieties have some effect on the activities.

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Late‐Stage Bromination Enables the Synthesis of Rubrolides B, I, K, and O

Cited by 17 publications

References 55 publications

Synthesis of new tetronamides displaying inhibitory activity against bloom‐forming cyanobacteria

Synthesis of new tetronamides displaying inhibitory activity against bloom‐forming cyanobacteria

Current Applications of Suzuki–Miyaura Coupling Reaction in The Total Synthesis of Natural Products: An update

Inibição Do Crescimento De Microrganismos Patogênicos Induzida Por Butenolídeos Análogos Aos Cadiolídeos

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