1,4-Addition reactions of lithium enolates to .alpha.,.beta.-unsaturated thioamides

1979 ◽  
Vol 101 (5) ◽  
pp. 1316-1318 ◽  
Author(s):  
Yoshinao Tamaru ◽  
Toshiro Harada ◽  
Zenichi Yoshida
Keyword(s):  
Addition Reactions ◽  
Lithium Enolates ◽  
Alpha Beta

Michael Addition Reactions of Unsaturated Esters with Lithium Enolates Derived from Vinylogous Urethanes

Heterocycles ◽  
1987 ◽  
Vol 25 (1) ◽  
pp. 315 ◽  
Author(s):  
Richard Schlessinger ◽  
Peter Lin ◽  
Michael Poss ◽  
James Springer
Keyword(s):  
Michael Addition ◽  
Addition Reactions ◽  
Unsaturated Esters ◽  
Lithium Enolates

1,3-Dioxan-5-ones: synthesis, deprotonation, and reactions of their lithium enolates

1995 ◽  
Vol 73 (10) ◽  
pp. 1616-1626 ◽  
Author(s):  
Marek Majewski ◽  
D. Mark Gleave ◽  
Pawel Nowak
Keyword(s):  
Enantiomeric Excess ◽  
Addition Reactions ◽  
Synthetic Route ◽  
Enol Ethers ◽  
Lithium Amide ◽  
Silyl Enol Ethers ◽  
Lithium Amides ◽  
Alkyl Groups ◽  
Lithium Enolates ◽  
Enantioselective Deprotonation

A general synthetic route to 2-alkyl- and 2,2-dialkyl-1,3-dioxan-5-ones, using tris(hydroxymethyl)-nitromethane as the starting material, is described. Deprotonation of these compounds was studied. It was established that these dioxanones could be deprotonated with LDA; however, the reduction of the carbonyl group via a hydride transfer from LDA, giving the corresponding dioxanols, often competed with deprotonation. The reduction could be minimized by using Corey's internal quench procedure to form silyl enol ethers and was less pronounced in 2,2-dialkyldioxanones (ketals) than in 2-alkyldioxanones (acetals). Self-aldol products were observed when dioxanone lithium enolates were quenched with H2O. Addition reactions of lithium enolates of dioxanones to aldehydes were threo-selective as predicted by the Zimmerman–Traxler model. Dioxanones having two different alkyl groups at the 2-position were deprotonated enantioselectively by chiral lithium amide bases with enantiomeric excess (ee) of up to 70%. Keywords: 1,3-dioxan-5-ones, enantioselective deprotonation, chiral lithium amides.

Highly Diastereoselective Michael Addition Reactions of Lithium Enolates to Ethyl 3-Trifluoromethylacrylate

1991 ◽  
Vol 20 (12) ◽  
pp. 2171-2174 ◽  
Author(s):  
Takashi Yamazaki ◽  
Jiro Haga ◽  
Tomoya Kitazume ◽  
Shinichiro Nakamura
Keyword(s):  
Michael Addition ◽  
Addition Reactions ◽  
Lithium Enolates
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