Radical-mediated hydroxyalkylation of α,β-unsaturated esters

Yajima, Tomoko; Saito, Chiaki; Nagano, Hajime

doi:10.1016/j.tet.2005.08.039

Cited by 37 publications

(13 citation statements)

References 50 publications

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“…36 Colorless liquid (348 mg, 61% yield); 1 H NMR (400 MHz, CDCl 3 ): δ (ppm) 2.59 (d, J = 7.1 Hz, 1H), 2.62 (d, J = 5.5 Hz, 1H), 2.76 (d, J =5.5 Hz, 1H), 2.79 (d, J = 7.2 Hz, 1H), 3.72 (s, 3H), 5.48 (dd, J = 2.7, 1.3 Hz, 1H), 6.14 (d, J = 1.3 Hz, 1H), 7. 13-7.20 (m, 3H), 7.22-7.29 (m, 2H).…”

Section: General Experimental Procedures For Ligand Screeningmentioning

confidence: 99%

Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand

et al. 2015

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Sarcosine was discovered to be an excellent ligand for cobalt-catalyzed carbon-carbon cross-coupling of Grignard reagents with allylic and vinylic bromides. The Co(II)/sarcosine catalytic system is shown to perform efficiently when phenyl and benzyl Grignards are coupled with alkenyl bromides. Notably, previously unachievable Co-catalyzed coupling of allylic bromides with Grignards to linearly coupled α-products was also realized with Co(II)/sarcosine catalyst. This method was used for efficient preparation of the key intermediate in an alternative synthesis of the antihyperglycemic drug sitagliptin.

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Section: General Experimental Procedures For Ligand Screeningmentioning

confidence: 99%

Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand

et al. 2015

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“…For example, OshimaUtimoto's group reported the reaction of CF 3 I with silyl and germyl enol ethers mediated by Et 3 B in the presence of nitrogen base such as 2,6-dimethylpyridine [132,133]. In 2003, Nagano and co-workers described the radical-mediated hydroxytrifluoromethylation of a,b-unsaturated esters in the presence of Et 3 B, water, and potassium fluoride in THF (Scheme 45) [134,135].…”

Section: Trifluoromethyl Iodidementioning

confidence: 99%

Strategies for nucleophilic, electrophilic, and radical trifluoromethylations

Ma¹,

Cahard²

2007

Journal of Fluorine Chemistry

543

177

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“…According to this mechanism, triethylborane would act as a multirole reagent inducing the radical initiation, radical termination, and reduction reactions. 47) Several experiments were conducted in support of our proposed reaction mechanism (Chart 8). In marked contrast to ester 7, the reaction of carboxylic acid 21 under the optimized hydroxyalkylation conditions gave the Michael-type adduct 22.…”

Section: Hydroxyalkylationmentioning

confidence: 82%

Radical Addition-Initiated Domino Reactions of Conjugated Oxime Ethers

Ueda

2014

CHEMICAL & PHARMACEUTICAL BULLETIN

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The application of conjugated oxime ethers to the synthesis of complex chemical scaffolds using domino radical reactions has been described in detail. The triethylborane-mediated hydroxysulfenylation reaction allows for the regioselective construction of a carbon-sulfur bond and a carbon-oxygen bond in a single operation for the formation of β-hydroxy sulfides. This reaction proceeds via a radical pathway involving regioselective thiyl addition and the subsequent trapping of the resulting α-imino radical with O₂, where the imino group enhances the stability of the intermediate radical. Hydroxyalkylation reactions that occur via a carbon radical addition reaction followed by the hydroxylation of the resulting N-borylenamine with O₂ have also been developed. We investigated sequential radical addition aldol-type reactions in detail to explore the novel domino reactions that occur via the generation of N-borylenamine. The radical reaction of a conjugated oxime ether with triethylborane in the presence of an aldehyde affords γ-butyrolactone via sequential processes including ethyl radical addition, the generation of N-borylenamine, an aldol-type reaction with an aldehyde, and a lactonization reaction. A novel domino reaction has also been developed involving the [3,3]-sigmatropic rearrangement of N-boryl-N-phenoxyenamine. The triethylborane-mediated domino reactions of O-phenyl-conjugated oxime ethers afforded the corresponding benzofuro[2,3-b]pyrrol-2-ones via a radical addition/[3,3]-sigmatropic rearrangement/cyclization/lactamization cascade.

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Radical-mediated hydroxyalkylation of α,β-unsaturated esters

Cited by 37 publications

References 50 publications

Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand

Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand

Strategies for nucleophilic, electrophilic, and radical trifluoromethylations

Radical Addition-Initiated Domino Reactions of Conjugated Oxime Ethers

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