Iridium-catalyzed oxidative lactonization and intramolecular Tishchenko reaction of δ-ketoaldehydes for the synthesis of isocoumarins and 3,4-dihydroisocoumarins

Suzuki, Takayoshi; Yamada, Taichiro; Watanabe, Kazuhiro; Katoh, Tadashi

doi:10.1016/j.bmcl.2005.03.043

Cited by 59 publications

(27 citation statements)

References 42 publications

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“…Mechanistically, the reaction was thought to proceed via the hemiacetal intermediate generated from the ketoaldehyde 82 that was oxidized by the iridium complex to give the product 83. The iridium hydride generated was oxidized by a cooxidant pivalaldehyde to regenerate the iridium complex [43].…”

Section: Ir-catalyzed Reactionmentioning

confidence: 99%

Isocoumarin and Its Derivatives: An Overview on their Synthesis and Applications

Pal¹,

Chatare²,

Pal³

2011

COC

179

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The prevalence of isocoumarins in numerous natural products that exhibit a wide range of biological activities has generated a continued and enormous interest among synthetic and medicinal chemists. The isocoumarin framework represents one of the privileged structures for the development of natural product-inspired compounds of potential biological interest. Considerable efforts have been devoted towards the synthesis of isocoumarins via either traditional or transition-metal catalyzed reactions. Among the metal catalyzed reactions, the use of Cu, Pd, Ag, Ru, Rh or Ir salts/complexes for the construction of isocoumarin ring are noteworthy. Among the other methodologies, halo-lactonization emerged as a practical process. Apart from preparing a variety of isocoumarins and thienopyranones, synthesis of naturally occurring and bioactive isocoumarins have been carried out by using cutting edge technologies. This review article will briefly cover all these aspects along with the synthetic utility of isocoumarins, highlighting recent developments.

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Section: Ir-catalyzed Reactionmentioning

confidence: 99%

Isocoumarin and Its Derivatives: An Overview on their Synthesis and Applications

Pal¹,

Chatare²,

Pal³

2011

COC

179

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“…The same catalyst has been used for an intramolecular variant of the reaction, where keto-aldehyde 92 isomerizes to lactone 93 via an intramolecular Tishchenko reaction. The oxidized product is formed as a by-product, and by running the reaction in the presence of an additional aldehyde as a hydrogen acceptor, the oxidized species 94 is formed as the sole product [82]. A related report has demonstrated that aldehydes can be converted into esters in the presence of allylic alcohols [83].…”

Section: Tishchenko Reactionmentioning

confidence: 96%

Iridium-Catalyzed Hydrogen Transfer Reactions

Saidi

Williams

2010

Iridium Catalysis

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This chapter describes the application of iridium complexes to catalytic hydrogen transfer reactions. Transfer hydrogenation reactions provide an alternative to direct hydrogenation for the reduction of a range of substrates. A hydrogen donor, typically an alcohol or formic acid, can be used as the source of hydrogen for the reduction of carbonyl compounds, imines, and alkenes. Heteroaromatic compounds and even carbon dioxide have also been reduced by transfer hydrogenation reactions. In the reverse process, the oxidation of alcohols to carbonyl compounds can be achieved by iridium-catalyzed hydrogen transfer reactions, where a ketone or alkene is used as a suitable hydrogen acceptor. The reversible nature of many hydrogen transfer processes has been exploited for the racemization of alcohols, where temporary removal of hydrogen generates an achiral ketone intermediate. In addition, there is a growing body of work where temporary removal of hydrogen provides an opportunity for using alcohols as alkylating agents. In this chemistry, an iridium catalyst "borrows" hydrogen from an alcohol to give an aldehyde or ketone intermediate, which can be transformed into either an imine or alkene under the reaction conditions. Return of the hydrogen from the catalyst provides methodology for the formation of amines or C-C bonds where the only by-product is typically water.

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“…While o-iodobenzoic acid 67 was reacted with Cu-acetylides to yield 3-benzylidinephthalide 68 instead of the formation of isocoumarin, the same acid upon reaction with phenyl acetylene in the presence of a catalytic amount of Cu(I)-PPh 3 and K 2 CO 3 under microwave atmosphere yielded isocoumarin 69 as a major product (Scheme 6). Marchal et al 93 carried out Au(I)-catalyzed intramolecular cyclization of esters 84a-84d to various alkylidene lactones 85. The electronic effects of the R group and bulky substituents on the alkyne strongly modify the reactivity.…”

Section: Synthesis Involving Metals/metal Ions/transition Metal Complmentioning

confidence: 99%

Isocoumarins and 3,4-dihydroisocoumarins, amazing natural products: a review

Saddiqa¹,

Çakmak²,

Usman³

2017

Turk J Chem

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Abstract:The isocoumarins are naturally occurring lactones that constitute an important class of natural products exhibiting an array of biological activities. A wide variety of these lactones have been isolated from natural sources and, due to their remarkable bioactivities and structural diversity, great attention has been focused on their synthesis. This review article focuses on their structural diversity, biological applications, and commonly used synthetic modes.

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Iridium-catalyzed oxidative lactonization and intramolecular Tishchenko reaction of δ-ketoaldehydes for the synthesis of isocoumarins and 3,4-dihydroisocoumarins

Cited by 59 publications

References 42 publications

Isocoumarin and Its Derivatives: An Overview on their Synthesis and Applications

Isocoumarin and Its Derivatives: An Overview on their Synthesis and Applications

Iridium-Catalyzed Hydrogen Transfer Reactions

Isocoumarins and 3,4-dihydroisocoumarins, amazing natural products: a review

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