Enantioselective Synthesis of α‐Alkyl‐β‐ketoesters: Asymmetric Roskamp Reaction Catalyzed by an Oxazaborolidinium Ion

Gao, Lizhu; Kang, Byung Chul; Hwang, Geum‐Sook; Ryu, Do Hyun

doi:10.1002/anie.201204350

Cited by 82 publications

(32 citation statements)

References 40 publications

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“…Despite not being the main topic of this review, the excellent levels of enantioselectivity achieved in the recent reports on the asymmetric homologation of aldehydes is worth noting. Namely, the Roskamp reaction can provide either α-substituted-β-ketoesters and derivatives with chiral catalysts − or auxiliaries or chiral all-carbon quaternary centers. , A similar approach using a chiral oxazaborolidinium ion as catalyst has been recently applied to the more challenging asymmetric homologation of aldehydes with noncarbonyl-stabilized aryldiazoalkanes …”

Section: Asymmetric Homologationsmentioning

confidence: 99%

Homologation Reaction of Ketones with Diazo Compounds

2016

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This review covers the addition of diazo compounds to ketones to afford homologated ketones, either in the presence or in the absence of promoters or catalysts. Reactions with diazoalkanes, aryldiazomethanes, trimethylsilyldiazomethane, α-diazo esters, and disubstituted diazo compounds are covered, commenting on the complex regiochemistry of the reaction and the nature of the catalysts and promoters. The recent reports on the enantioselective version of ketone homologation reactions are gathered in one section, followed by reports on the use of cyclic ketones ring expansion in total synthesis. Although the first reports of this reaction appeared in the literature almost one century ago, the recent achievements, in particular, for the asymmetric version, forecast the development of new breakthroughs in the synthetically valuable field of diazo chemistry.

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Section: Asymmetric Homologationsmentioning

confidence: 99%

Homologation Reaction of Ketones with Diazo Compounds

2016

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“…The observed stereochemistry for enantioselective formation of trisubstituted α,β‐ Z ‐epoxy ester with COBI catalyst 1 e can be rationalized on the basis of the transition‐state model shown in Figure 2. The coordination mode of the phenyl glyoxal to catalyst 1 e and the enantioselective carbonyl addition of phenyl diazoester are the same as have been observed for the asymmetric Roskamp reaction [12b–e] . In the pre‐transition‐state assembly 4 , shown in Figure 2.…”

Section: Methodsmentioning

confidence: 61%

“…Recently, our group reported highly enantioselective catalytic tandem reactions of diazo compounds with the chiral oxazaborolidinium ion (COBI) [12, 13] as a Lewis acid catalyst. After forming tetrahedral intermediate through nucleophilic addition of diazo compounds into aldehyde, H‐migration [12a–d] (Roskamp reaction, path a) and C‐migration (path b) [12e] led to the construction of optically active β‐keto ester and the all‐carbon quaternary aldehyde, respectively (Scheme 1 B). However, epoxide products were observed as side products in the case of o ‐fluorobenzaldehyde [12a] .…”

Section: Methodsmentioning

confidence: 99%

Catalytic Asymmetric Darzens‐Type Epoxidation of Diazoesters: Highly Enantioselective Synthesis of Trisubstituted Epoxides

et al. 2021

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Highly enantioselective Darzens‐type epoxidation of diazoesters with glyoxal derivatives was accomplished using a chiral boron–Lewis acid catalyst, which facilitated asymmetric synthesis of trisubstituted α,β‐epoxy esters. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction proceeded in high yield (up to 99 %) with excellent enantio‐ and diastereoselectivity (up to >99 % ee and >20:1 dr, respectively). The synthetic potential of this method was illustrated by conversion of the products to various compounds such as epoxy γ‐butyrolactone, tertiary β‐hydroxy ketone and epoxy diester.

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“…The asymmetric reaction between propanal and 2-azopropionate produced a (S)-a-methyl-b-ketoester, which was reduced with Zn(BH 4 ) 2 to afford (2S,3R)-82 (R-4-5). 251 (5) Synthesis via a chemoenzymatic reaction. The synthetic route for (4R,8R)-29 was designed by applying a lipase-catalyzed resolution at two steps (R-5-1a).…”

Section: Application Of Stereoselective Reactionsmentioning

confidence: 99%

Chiral methyl-branched pheromones

Ando

Yamakawa

2015

Nat. Prod. Rep.

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Insect pheromones are some of the most interesting natural products because they are utilized for interspecific communication between various insects, such as beetles, moths, ants, and cockroaches. A large number of compounds of many kinds have been identified as pheromone components, reflecting the diversity of insect species. While this review deals only with chiral methyl-branched pheromones, the chemical structures of more than one hundred non-terpene compounds have been determined by applying excellent analytical techniques. Furthermore, their stereoselective syntheses have been achieved by employing trustworthy chiral sources and ingenious enantioselective reactions. The information has been reviewed here not only to make them available for new research but also to understand the characteristic chemical structures of the chiral pheromones. Since biosynthetic studies are still limited, it might be meaningful to examine whether the structures, particularly the positions and configurations of the branched methyl groups, are correlated with the taxonomy of the pheromone producers and also with the function of the pheromones in communication systems.

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Enantioselective Synthesis of α‐Alkyl‐β‐ketoesters: Asymmetric Roskamp Reaction Catalyzed by an Oxazaborolidinium Ion

Cited by 82 publications

References 40 publications

Homologation Reaction of Ketones with Diazo Compounds

Homologation Reaction of Ketones with Diazo Compounds

Catalytic Asymmetric Darzens‐Type Epoxidation of Diazoesters: Highly Enantioselective Synthesis of Trisubstituted Epoxides

Chiral methyl-branched pheromones

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