Total Synthesis of Carbazomycins A and B

Wu, Siyuan; Harada, Satoru; Morikawa, Takahiro; Nishida, Atsushi

doi:10.1248/cpb.c17-00851

Cited by 15 publications

(18 citation statements)

References 34 publications

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“…In this report we wish to underline the usefulness of our developed methodology by further describing concise syntheses of naturally occurring 3-oxygenated carbazole alkaloids -6-chlorohyellazole, 32 carazostatin, 33 and the 3,4-dioxygenated carbazole natural products carbazomycins A and B. 34 The diyne-ynamides 2a-c were prepared from the readily available precursors 5 and 8, which were synthesized from the commercially available 2-iodoanilines 4 and 7 respectively (Scheme 2). The N-ethynylation of anilide 5 with alkynyl iodonium salt 6 delivered 2a (X = Cl, R 1 = Ph) in 60% isolated yield.…”

Section: Figure 1 Selected Naturally Occurring 3-oxygenated Carbazolesmentioning

confidence: 99%

Rhodium-Catalyzed Crossed [2+2+2] Cycloaddition with Ynamides: Key-Strategy for the Concise Total Synthesis of 3-Oxygenated Carbazole Alkaloids

Witulski¹,

Alayrac²

2021

HETEROCYCLES

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Total syntheses of a set of naturally occurring 3-oxygenated carbazole alkaloids -6-chlorohyellazole, carazostatin, carbazomycins A and B -are described. The key-strategy underlines a highly chemo-and regioselective rhodium-catalyzed [2+2+2] cyclotrimerization between appropriately tailored yne-ynamides and 1-methoxypropyne that is stirred by the interplay o f stereoelectronic and steric effects allowing the introduction of four rin g substituents of the natural carbazoles within a single step and making the overall syntheses short and efficient.Carbazole alkaloids are an important class of natural products displaying high diversity in their substitution pattern and revealing a broad range of biological activities. 1 In the case of 3-hydroxycarbazole alkaloids, an alkyl chain is typically displayed at position C-1 but some exceptions are found. For example, hyellazole and 6-chlorohyellazole have the particularity of bearing a phenyl group at this position (Figure 1). Both are of marine origin and have been isolated from the blue-green alga Hyella caespitosa. 2 Other 3-hydroxycarbazoles such as antiostatin A1, 3 carazostatin, 4 and the carbazomycins 5 A and B were isolated from micro-organisms, Streptomyces cyaneus 2007-SV1, Streptomyces chromofuscus, and Streptoverticillium ehimense H1051-MY 10, respectively.Very recently, the carbazomycin B producing strain Streptomyces luteoverticillatus SZJ61 was isolated from marine sediment in China. 6 Carbazomycins A and B are the first carbazole-related antibiotics possessing weak antibacterial and antiyeast activity and inhibit the growth of some phytopathogenic fungi. 5a,6 Carbazomycin A displays weak cytotoxicity against cancerous (MCF-7, KB, NCI-H187) and non-

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Section: Figure 1 Selected Naturally Occurring 3-oxygenated Carbazolesmentioning

confidence: 99%

Rhodium-Catalyzed Crossed [2+2+2] Cycloaddition with Ynamides: Key-Strategy for the Concise Total Synthesis of 3-Oxygenated Carbazole Alkaloids

Witulski¹,

Alayrac²

2021

HETEROCYCLES

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“…After the removal of oxazolidone, compound 44 was treated with copper chloride and cesium fluoride, and hydrocarbazolone 46 was obtained via 45 in 96% yield. They also achieved the synthesis of carbazomycins by a racemic Diels‐Alder reaction …”

Section: Heterocycle‐fused Siloxydienesmentioning

confidence: 99%

Catalytic and Enantioselective Diels‐Alder Reaction of Siloxydienes

Harada

Nishida

2019

Asian J Org Chem

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Diels-Alder reaction is one of the most well-known named reactions in organic chemistry. It involves a diene substrate and a dienophile substrate. Among dienes, siloxydiene is a reactive substrate that is often used in Diels-Alder reaction. In general, Diels-Alder reaction is promoted by an acidic reagent. In many cases, the stereoselectivity of the reaction is also controlled by acids. However, siloxydienes are labile under acidic conditions. Thus, it should be difficult to develop a reaction using siloxydiene as a substrate. Never-theless, siloxydienes are still used in synthetic organic chemistry, and most reactions are performed under thermal activation conditions. In this minireview, we summarize the reported examples of catalytic and enantioselective Diels-Alder reactions of siloxydienes based on the structure of the diene. We present the activation methods used, the existing problems, and a clue for the further development of this annulation chemistry. 2 3 4 5 6 7 8

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“…Carbazole is one such versatile heterocyclic scaffold, obtained either from natural or by synthesis . The synthesis of novel carbazole derivatives and the investigation of their chemical and biological behavior have gained importance in recent decades for their biological, medicinal and photoelectrical applications . Although carbazole is a rigid moiety, but can easily be functionalized to develop novel bioactive molecules.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Biological Evaluation of Novel Carbazole Hybrids as Promising Antimicrobial Agents

Shaikh

Chandrasekaran

Palkar

et al. 2020

Chemistry & Biodiversity

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Two series of carbazole analogs of 8-methoxy-N-substituted-9H-carbazole-3-carboxamides (series 1) and carbazolyl substituted rhodanines (series 2) were synthesized through facile synthetic routes. All the final compounds from these two series were evaluated for their preliminary in vitro antifungal and antibacterial activity against four fungal (Candida albicans, Cryptococcus neoformans, Cryptococcus tropicalis and Aspergillus niger) and four bacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) strains, respectively. Among the tested compounds, three compounds of series 1 displayed promising antifungal and antibacterial activity, especially against C. neoformans and S. aureus. In addition, one compound of series 1 displayed notable antimicrobial activity (MIC: 6.25 μg/mL) against clinical isolates of C. albicans and C. neoformans (MIC: 12.5 μg/mL). From the second series, four compounds exhibited significant antifungal and antibacterial activity, especially against C. neoformans and S. aureus. The most active compound of series 2 displayed a prominent antimicrobial activity against C. neoformans (MIC: 3.125 μg/mL) and S. aureus (MIC: 1.56 μg/mL), respectively.

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Total Synthesis of Carbazomycins A and B

Cited by 15 publications

References 34 publications

Rhodium-Catalyzed Crossed [2+2+2] Cycloaddition with Ynamides: Key-Strategy for the Concise Total Synthesis of 3-Oxygenated Carbazole Alkaloids

Rhodium-Catalyzed Crossed [2+2+2] Cycloaddition with Ynamides: Key-Strategy for the Concise Total Synthesis of 3-Oxygenated Carbazole Alkaloids

Catalytic and Enantioselective Diels‐Alder Reaction of Siloxydienes

Synthesis and Biological Evaluation of Novel Carbazole Hybrids as Promising Antimicrobial Agents

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