Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Enol phosphates reaction with dialkylcuprates

This procedure illustrates a new method for the preparation of 6-alkyl-a,g-unsaturated esters by coupling lithium dialkylcuprates with enol phosphates of g-keto esters. The procedure for the preparation of methyl 2-oxocyclohexanecarboxylate described in Part A Is based on one reported by Ruest, Blouin, and Deslongcharaps. Methyl 2-methyl-l-cyc1ohexene-l-carboxylate has been prepared by esterification of the corresponding acid with dlazomethane - and by reaction of methyl 2-chloro-l-cyclohexene-l-carboxyl ate with lithium dimethylcuprate. -... [Pg.21]

The formation of g-alkyl-a,g-unsaturated esters by reaction of lithium dialkylcuprates or Grignard reagents in the presence of copper(I) iodide, with g-phenylthio-, > g-acetoxy-g-chloro-, and g-phosphoryloxy-a,g-unsaturated esters has been reported. The principal advantage of the enol phosphate method is the ease and efficiency with which these compounds may be prepared from g-keto esters. A wide variety of cyclic and acyclic g-alkyl-a,g-unsaturated esters has been synthesized from the corresponding g-keto esters. However, the method is limited to primary dialkylcuprates. Acyclic g-keto esters afford (Zl-enol phosphates which undergo stereoselective substitution with lithium dialkylcuprates with predominant retention of stereochemistry (usually > 85-98i )). It is essential that the cuprate coupling reaction of the acyclic enol phosphates be carried out at lower temperatures (-47 to -9a°C) to achieve high stereoselectivity. When combined with they-... [Pg.21]


See other pages where Enol phosphates reaction with dialkylcuprates is mentioned: [Pg.128]    [Pg.218]   
See also in sourсe #XX -- [ Pg.3 , Pg.218 ]

See also in sourсe #XX -- [ Pg.218 ]

See also in sourсe #XX -- [ Pg.3 , Pg.218 ]




SEARCH



Dialkylcuprates

Enol phosphate

Enolization phosphate

Enols reactions with

Phosphation reactions

Reactions, with enolates

© 2024 chempedia.info