Enantioselective Synthesis of Altohyrtin C (Spongistatin 2): Synthesis of the AB‐ and CD‐Spiroketal Subunits

Evans, David A.; Coleman, Paul J.; Dias, Luiz C.

doi:10.1002/anie.199727381

Cited by 115 publications

(31 citation statements)

References 42 publications

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“…The first total syntheses of altohyrtin C and altohyrtin A by the groups of Evans [16] and Kishi [17], respectively, confirmed the stereochemical assignments proposed by Kitagawa and Kobayashi and demonstrated the identity of spongistatin 2 to altohyrtin C and spongistatin 1 to altohyrtin A.…”

Section: Isolation Structures and Biological Activitiessupporting

confidence: 74%

“…Total synthesis of altohyrtin C/spongistatin 2 by Evans [16] Evans and co-workers proposed a versatile strategy as far as stereochemistry is concerned because of the discrepancies existing at that time between altohyrtins and spongistatins. Assembly of AB and CD spiroketals was envisaged by acid mediated cyclization of linear keto polyol precursors.…”

Section: Total Syntheses Of Altohyrtins/spongistatinsmentioning

confidence: 99%

“…Total syntheses of spongistatins/altohyrtins have been reported by seven groups (Evans [16], Kishi [17], Smith [19,20], Paterson [21], Crimmins [22], Heathcock [23] and Ley [24]) each presenting different practical solutions for the assembly of the ABCD and EF key fragments. The bis-spiroketal subunit can be constructed through an anti-aldol reaction to form the C(15)eC (16) bond or via a KishieNozaki coupling to produce the C(17)eC (18) linkage. Sulfone alkylation at C (14) also gives rise to the same fragment.…”

Section: Isolation Structures and Biological Activitiesmentioning

confidence: 99%

See 2 more Smart Citations

Spongistatins: Biological activity and synthetic studies

Gerber‐Lemaire

Vogel

2008

Comptes Rendus. Chimie

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Section: Isolation Structures and Biological Activitiessupporting

confidence: 74%

Section: Total Syntheses Of Altohyrtins/spongistatinsmentioning

confidence: 99%

Section: Isolation Structures and Biological Activitiesmentioning

confidence: 99%

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Spongistatins: Biological activity and synthetic studies

Gerber‐Lemaire

Vogel

2008

Comptes Rendus. Chimie

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“…O intermediário avançado 21 foi utilizado na síntese do produto natural marinho altoirtina C (espongistatina 2) [30][31][32][33] .…”

Section: Reações Aldólicas Com Estereoindução 15-antiunclassified

Indução assimétrica 1,5-Anti na adição de enolatos de boro de metilcetonas beta-oxigenadas a aldeídos

Dias¹,

Aguilar²

2007

Quím. Nova

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# Esta revisão é dedicada à Prof a . Helena M. C. Ferraz em reconhecimento a sua grande contribuição acadêmica e científica para a área de Química Orgânica no Brasil. High levels of substrate-based 1,5-stereoinduction are obtained in the boron-mediated aldol reactions of β-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate π-facial selectivity critically dependent upon the nature of the β-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed. INDUÇÃO ASSIMÉTRICA 1,5-ANTI NA ADIÇÃO DE ENOLATOS DE BORO DE METILCETONASKeywords: 1,5-anti induction; boron enolates; aldol reactions. INTRODUÇÃOA reação aldólica é seguramente um dos métodos mais poderosos para a formação de ligações carbono-carbono 1-7 . Esta reação representa uma ferramenta muito útil na construção de fragmentos com alta complexidade estrutural e com elevados níveis de seletividade, sendo bastante empregada na síntese assimétrica de produtos naturais com atividade farmacológica destacada 8,9 . A incorporação de convergência na construção de policetídeos requer que fragmentos complexos sejam acoplados em algum ponto da rota sintética e, neste sentido, a reação aldólica representa um mé-todo extremamente útil.Os fatores responsáveis pelo controle da estereosseletividade na reação aldólica envolvendo enolatos metálicos estão relacionados com a natureza do átomo do ácido de Lewis utilizado (B, Li, Zn, Ti, Mg etc); a geometria da dupla ligação do enolato preparado (Z ou E); a presença de centros estereogênicos no enolato, no aldeído, ou no ácido de Lewis; o volume e a natureza dos substituintes nos substratos e, as condições reacionais.Em termos gerais, a estereoquímica relativa esperada para os produtos de reações aldólicas envolvendo enolatos de boro E e Z pré-formados é bastante previsível. A reação aldólica com enolatos de boro Z fornece o aduto de aldol syn, e com enolatos de boro E, o aduto de aldol anti, como está delineado no Esquema 1. Estas reações passam por estados de transição cíclico-quelados, do tipo cadeira, como proposto por Zimmerman-Traxler (Esquema 1) 4,10,11 . Neste modelo observa-se que o controle da diastereosseletividade é dependente do volume do substituinte presente no aldeído, que preferencialmente ocupa uma posição pseudo-equatorial no estado de transição tipo cadeira, eliminando dessa maneira a interação 1,3-diaxial desfavorável entre o grupo R e o grupo X.Os parâmetros estéricos influenciam fortemente na formação de estados de transição diastereoisoméricos e, conseqüentemente, na estereoquímica dos produtos obtidos (a geometria do enolato se transfere para o produto em um processo altamente diastereosseletivo). Os dialquil...

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“…[15][16][17] To overcome the low abundance of this natural product, seven total syntheses have been developed to date. 18 In an electronically complementary process, Evans and Gauchet-Prunet developed an efficient method to produce benzylidene acetal-protected 1,3-syn-diols. Treatment of ester 33 with benzaldehyde and potassium alkoxide efficiently generated the syn-1,3-dioxane 34 with high stereocontrol (Scheme 37.9).…”

Section: Formation Of 13-diols From Homoallylic Alcohol Derivativesmentioning

confidence: 99%

Ether Transfer Methodology: Application to the Synthesis of Polyketide Natural Products

Stefan

Taylor

2013

Stereoselective Synthesis of Drugs and Natural Products

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This chapter comprises two major components that sequentially describe existing methods pertinent to the stereoselective formation of 1,3‐ syn ‐diol functionality and the development of a new approach to 1,3‐ syn ‐diol monoethers and diethers through electrophilic activation of homoallylic alkoxymethyl ethers. The ability to quench a key chloromethyl ether intermediate with various nucleophiles highlights the versatility of the ether transfer method. The process provides selective access to either diol‐monoethers or diethers, and it describes an opportunity to convert acyclic stereochemically rich fragments into highly functionalized pyran systems. This fundamentally new method was successfully applied to the synthesis of several complex polyketides including the synthesis of isotactic polyethers, the C7–C17 fragment of swinholide A, the C3–C17 fragment of phorboxazole A, and the neopeltolide macrolactone.

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Enantioselective Synthesis of Altohyrtin C (Spongistatin 2): Synthesis of the AB‐ and CD‐Spiroketal Subunits

Cited by 115 publications

References 42 publications

Spongistatins: Biological activity and synthetic studies

Spongistatins: Biological activity and synthetic studies

Indução assimétrica 1,5-Anti na adição de enolatos de boro de metilcetonas beta-oxigenadas a aldeídos

Ether Transfer Methodology: Application to the Synthesis of Polyketide Natural Products

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