Organocatalytic Asymmetric Direct α‐Alkynylation of Cyclic β‐Ketoesters.

Poulsen, Thomas B.; Bernardi, Luca; Alemán, J.; Overgaard, Jacob; Joergensen, Karl Anker

doi:10.1002/chin.200723030

Cited by 6 publications

(18 citation statements)

References 6 publications

(13 reference statements)

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“…In the two last decades, ynamines and ynamides have become 35 increasingly important in chemical transformations. 7,8 For example, these compounds can undergo α or β addition, oxidation, reduction, cycloaddition or ring-closing metathesis.…”

Section: C-n Bond Formationmentioning

confidence: 99%

“…Similarly to nitrogen and oxygen, a range of methods have been developed for the reaction of electrophilic acetylenes with sulfur 35 nucleophiles. One interesting application was reported by Wipf and Venkatraman for the synthesis of thiazoles (Scheme 15).…”

Section: C-s Bond Formationmentioning

confidence: 99%

“…In order to facilitate Kende's addition-elimination mechanism with these mild nucleophiles, Jørgensen and coworkers introduced further electron-withdrawing groups such as ketones, amides, esters and sulphones onto the acetylene (Scheme 23). 35 With these reagents, the alkynylation became possible 80 under mild phase-transfer conditions, which allowed the first highly efficient enantioselective alkynylation of cyclic ketoesters when cinchonidine-derived catalyst 12 was used. Particularly interesting was the use of allyl-substituted propiolates, as the obtained esters can be easily decarboxylated using a palladium 5 catalyst.…”

Section: Scheme 22mentioning

confidence: 99%

“…3 The reverse approach, the electrophilic alkynylation of the nucleophilic -position of a carbonyl group or an electron-rich C-H or C-metal bond on an aromatic compound is usually not considered (Scheme 1, B). In this case, the normal reactivity of alkynes would need to be 35 inverted (an Umpolung in its broader sense). This is not an easy task, but it has the potential to make acetylene synthesis much more flexible, which would have an enormous impact on applications.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, a first example of asymmetric induction with 40% enantioselectivity was achieved using a non-soluble fluoride source and a cinchonidine-derived phase transfer catalyst 12. Although the 35 enantioselectivity was still low, it was the first time that asymmetric induction was observed for the alkynylation of enolates using hypervalent iodine reagents.…”

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confidence: 99%

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Electrophilic alkynylation: the dark side of acetylene chemistry

2012

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In addition to the well-established nucleophilic alkynylation, the use of electrophilic alkynes can expand 5 tremendously the scope of acetylene transfer reactions. The use of metal catalysis has recently led to a rebirth of this research area. Halogenoalkynes, hypervalent alkynyliodoniums, acetylene sulfones and in situ oxidation of terminal acetylenes are the most often used for electrophilic alkynylation. Heteroatoms such as N, O, S and P can be now efficiently alkynylated. For C-C bond formation, electrophilic acetylenes can be coupled with different organometallics reagents. Recently, the first breakthrough in 10 direct C-H and C=C bond alkynylation have also been reported. Finally, sulfonyl acetylenes are efficient for alkyne transfer on carbon-centered radicals.

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Section: C-n Bond Formationmentioning

confidence: 99%

Section: C-s Bond Formationmentioning

confidence: 99%

Section: Scheme 22mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Electrophilic alkynylation: the dark side of acetylene chemistry

2012

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Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

2016

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Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

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Enantioselective Organocatalyzed Transformations of β-Ketoesters

et al. 2016

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The β-ketoester structural motif continues to intrigue chemists with its electrophilic and nucleophilic sites. Proven to be a valuable tool within organic synthesis, natural product, and medicinal chemistry, reports on chiral β-ketoester molecular skeletons display a steady increase. With the reignition of organocatalysis in the past decade, asymmetric methods available for the synthesis of this structural unit has significantly expanded, making it one of the most exploited substrates for organocatalytic transformations. This review provides comprehensive information on the plethora of organocatalysts used in stereoselective organocatalyzed construction of β-ketoester-containing compounds.

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Organocatalytic Asymmetric Direct α‐Alkynylation of Cyclic β‐Ketoesters.

Cited by 6 publications

References 6 publications

Electrophilic alkynylation: the dark side of acetylene chemistry

Electrophilic alkynylation: the dark side of acetylene chemistry

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Enantioselective Organocatalyzed Transformations of β-Ketoesters

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