- Lithium naphthalenide induced reductive alkylation of α-cyano ketones. A general method for regiocontrol of α,α-dialkylation of ketones
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An efficient general method for the consecutive introduction of two alkyl groups to the α carbon of a ketone carbonyl has been developed, making use of the lithium naphthalenide induced reductive alkylation of an α-cyano ketone system as a key operation.
- Liu, Hsing-Jang,Zhu, Jia-Liang,Shia, Kak-Shan
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p. 4183 - 4186
(2007/10/03)
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- Thioalkylation of Enolates, II. α-Thioalkylation of Zinc Enolates to α,α-Disubstituted Ketones
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An α-alkylation of the 2-methylcycloalkanones 1 and 4 at the higher substituted carbon can be achieved by thioalkylation of the corresponding zinc enolates with the α-chlorosulfides 3.The desulfurization can be carried out with either Raney nickel or lithium in diethylamine for compounds which contain double or triple bonds. Key Words: Zinc enolates, thioalkylation of / Ketones, α,α-disubstituted / Desulfurization
- Groth, Ulrich,Huhn, Thomas,Richter, Norbert
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- α-ALKYLATION AND α-ALKYLIDENATION OF CARBONYL COMPOUNDS BY O-SILYLATED ENOLATE PHENYLTHIOALKYLATION
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For many reactions next to a carbonyl group, the use of O-silylated enolate chemistry offers improvements in yield and selectivity over the corresponding reactions of Group I metal enolates.In the case of α-alkylation of carbonyl compounds, Lewis acid (TiCl4 or ZnBr2) promoted phenylthioalkylation of O-silylated enolates 3 by α-chlorosulphides 4 (R3=H, Me, Prn, Pri, Bui, and Me3Si), followed by reductive sulphur removal by Raney nickel, 5->6, is found to be a reliable method for this synthetically important C-C bond forming step.An alternative sulphur elimination pathway via the sulphoxide, 5->7, allows the regio- and stereocontrolled α-alkylidenation of carbonyl compounds.The phenylthioalkylation reaction is applicable to ketones, aldehydes, esters, and lactones.
- Paterson, Ian
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p. 4207 - 4220
(2007/10/02)
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- Absolute Configuration of 1,2-Disubstituted trans-Cyclodecenes Based on Chemical Correlation with (+)-Dimethyl (2R)-2-Butyl-1-methyloctanedioate
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The absolute configuration of (-)-trans-1,2-dimethylcyclodecene (4) has been determined to be R through chemical correlation with (+)-dimethyl (2R)-2-butyl-2-methyloctanedioate (13).Diester 13 was prepared from (+)-(4aS)-4a-methyl-2,3,4,4a,5,6,7,8-octahyd
- Marshall, James A.,Flynn, Katherine E.
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p. 7430 - 7435
(2007/10/02)
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- Fluoride-Mediated Reactions of Enol Silyl Ethers. Regiospecific Monoalkylation of Ketones
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Treatment of enol silyl ethers with alkyl halides in the presence of benzyltrimethylammonium fluoride and molecular sieves at room temperature gives the corresponding monoalkylated products with high regiospecificity.In most cases no polyalkylated products formed in the reaction.The alkylation reaction is highly chemospecific: esters, epoxides, and even ketones survive the reaction conditions.The reactions of various cyclohexanone derivatives proceed with the preferential axial attack of the electrophile.
- Kuwajima, Isao,Nakamura, Eiichi,Shimizu, Makoto
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p. 1025 - 1030
(2007/10/02)
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