- Aldehydes as alkyl carbanion equivalents for additions to carbonyl compounds
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Nucleophilic addition reactions of organometallic reagents to carbonyl compounds for carbon-carbon bond construction have played a pivotal role in modern chemistry. However, this reaction's reliance on petroleum-derived chemical feedstocks and a stoichiometric quantity of metal have prompted the development of many carbanion equivalents and catalytic metal alternatives. Here, we show that naturally occurring carbonyls can be used as latent alkyl carbanion equivalents for additions to carbonyl compounds, via reductive polarity reversal. Such 'umpolung' reactivity is facilitated by a ruthenium catalyst and diphosphine ligand under mild conditions, delivering synthetically valuable secondary and tertiary alcohols in up to 98% yield. The unique chemoselectivity exhibited by carbonyl-derived carbanion equivalents is demonstrated by their tolerance to protic reaction media and good functional group compatibility. Enantioenriched tertiary alcohols can also be accessed with the aid of chiral ligands, albeit with moderate stereocontrol. Such carbonyl-derived carbanion equivalents are anticipated to find broad utility in chemical bond formation.
- Wang, Haining,Dai, Xi-Jie,Li, Chao-Jun
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p. 374 - 378
(2017/04/03)
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- CeCl3·7H2O-Nal Catalyzed Hydrooxacyclization of Unsaturated 3-Hydroxy Esters
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(Matrix Presented) Cerium(III) chloride heptahydrate and sodium iodide in boiling acetonitrile promote cyclization of 3-hydroxyalkenoic acids esters giving 5-substituted tetrahydrofuranacetic acid esters and 6-substituted tetrahydropyranacetic acid esters
- Marotta, Emanuela,Foresti, Elisabetta,Marcelli, Tommaso,Peri, Francesca,Righi, Paolo,Scardovi, Noemi,Rosini, Goffredo
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p. 4451 - 4453
(2007/10/03)
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- A General Approach to the Synthesis of Butanolides: Synthesis of the Sex Pheromone of the Japanese Beetle
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A variety of substituted γ-hydroxy olefins 1 have been converted to butanolides 4 in very high yield in a three-step sequence involving bromoetherification, elimination, and oxidative cleavage.The key step in the overall transformation is the highly selective oxidative cleavage of enol ethers 3 with PCC under very mild reaction conditions.Application of this methodology has been exemplified in the synthesis of the Japanese beetle pheromone.
- Baskaran, Sundarababu,Islam, Imadul,Chandrasekaran, Srinivasan
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p. 891 - 895
(2007/10/02)
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