Nickel/Lewis Acid-Catalyzed Cyanoesterification and Cyanocarbamoylation of Alkynes

Hirata, Yasuhiko; Yada, Akira; Morita, Eiji; Nakao, Yoshiaki; Hiyama, Tamejiro; Ohashi, Masato

doi:10.1021/ja102346v

Cited by 190 publications

(69 citation statements)

References 144 publications

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“…11 In a similar fashion, the Polonovski-Potier reaction is initialized on 4 to promote the facile release of trifluoroacetate and subsequent C-C bond scission of the macrocycle (Scheme 3). 11 Following formaldehyde extrusion, the ring re-forms and provides access to the vallesamine (5). These data provided inspiration for the recent total synthesis of the structurally re- (2) anhydrovinblastine (3) vinblastine (1) Scheme 2 Mechanism for the conversion of anhydrovinblastine (2) into vinorelbine (3) lated natural product conolidine by Micalizio and coworkers.…”

Section: Figure 1 Structures Of Vinblastine Vinorelbine and Anhydromentioning

confidence: 94%

Cleaving Carbon-Carbon Bonds by the Release of Trifluoroacetate to Remodel Molecules and Assemble Fluorinated Structures

Han

Kim

Colby

2012

Synlett

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Cleaving carbon-carbon bonds is a significant synthetic challenge. The release of trifluoroacetate presents a powerful force to break these strong bonds. Herein, a brief review of the role of the release of trifluoroacetate in remodeling organic molecules and synthesizing fluorinated compounds is presented.Trifluoroacetate is used as an activating group to induce the elimination of alcohols and is a common counterion in many synthetic reactions. Additionally, a trifluoroacetyl group can serve as a protecting group. The advantages of a trifluoroacetyl group over an acetyl group are due to the exchange of each of the α-protons with electronegative fluorine atoms. Specifically, these fluorine atoms strongly polarize the adjacent carbonyl group and terminate the tendency of enolate formation from base compared with an acetyl group. Trifluoroacetate has another powerful, yet widely underexplored application, namely it can promote the cleavage of carbon-carbon bonds during its release from an organic molecule. Although breaking carbon-carbon bonds is quite difficult and rarely explored by synthetic chemists, 1-6 studying bond cleavage through trifluoroacetate release presents opportunities to remodel molecular structures as well as generate reactive intermediates. 3 In this review, key advances in the scission of carbon-carbon bonds through the release of trifluoroacetate are presented, along with the applications of the respective reactive intermediates in organic synthesis and medicinal chemistry. The release of trifluoroacetate poses two major pathways to cleave bonds, elimination and fragmentation (Scheme 1). The first part of this review will describe examples of trifluoroacetate release by elimination to generate cationic intermediates to remodel organic structures, and the second part will detail cases of trifluoroacetate release by fragmentation to produce anions to assemble fluorinated molecules.

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Section: Figure 1 Structures Of Vinblastine Vinorelbine and Anhydromentioning

confidence: 94%

Cleaving Carbon-Carbon Bonds by the Release of Trifluoroacetate to Remodel Molecules and Assemble Fluorinated Structures

Han

Kim

Colby

2012

Synlett

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“…Nakao, Hiyama, and co-workers reported an intramolecular arylcyanation reaction of alkenes that was cooperatively catalyzed by nickel and AlMe 2 Cl (Scheme 34). [40] Treatment of the substrate with [NiA C H T U N G T R E N N U N G (cod) 2 ] (5 mol %), PMe 3 (10 mol %), and AlMe 2 Cl (20 mol %) in toluene gave compound 229 in 93 % yield, which was derived from the insertion of the olefinic moiety into the ArÀCN bond in a 5-exo-trig fashion. Larger-ring systems, including six-and seven-membered compounds, have been successfully constructed.…”

Section: à Cn Bond Cleavagementioning

confidence: 99%

Unstrained CarbonCarbon Bond Cleavage

Liu

Feng

Jiang

2014

Chemistry An Asian Journal

115

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This Focus Review presents recent developments in the cleavage of C-C bonds in organic molecules. Significant progress in C-C activation, including the development of a variety of new synthetic strategies, has contributed to the development of this field over the past few decades. Transition-metal-mediated C-C bond cleavage has been shown to be a quite efficient process and several elegant metal-free methods have also recently been developed. Strained rings have been widely used in C-C cleavage transformations; however, unstrained C-C activation has increasingly caught the attention of organic researchers, which inspired us to clarify the developments in this field.

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“…35,36 Electron-deficient alkynes, such as alkynyl cyanides, are susceptible to homo and/or crosstrimerization reactions when only a nickel catalyst is used. 38 Once again, the reaction is only efficient in the presence of a Lewis acid cocatalyst. 35 Compared to other aluminumbased Lewis acid catalysts that are effective for arylcyanation reactions, 34 triarylboranes such as triphenylboron and tris(pentafluorophenyl)boron are more effective for alkynylcyanation reactions.…”

Section: Triphenylboron As a Phenyl-transfer Reagentmentioning

confidence: 99%