Lithium amide catalyzed amine-olefin addition reactions

1972 ◽  
Vol 37 (26) ◽  
pp. 4243-4245 ◽  
Author(s):  
Richard J. Schlott ◽  
John Carl. Falk ◽  
Kenneth W. Narducy
Keyword(s):  
Addition Reactions ◽  
Lithium Amide

ChemInform Abstract: Asymmetric Syntheses of Dihydroxyhomoprolines via Doubly Diastereoselective Lithium Amide Conjugate Addition Reactions.

ChemInform ◽  
2014 ◽  
Vol 45 (7) ◽  
pp. no-no
Author(s):  
Stephen G. Davies ◽  
Emma M. Foster ◽  
James A. Lee ◽  
Paul M. Roberts ◽  
James E. Thomson
Keyword(s):  
Conjugate Addition ◽  
Addition Reactions ◽  
Asymmetric Syntheses ◽  
Lithium Amide

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.

Asymmetric syntheses of dihydroxyhomoprolines via doubly diastereoselective lithium amide conjugate addition reactions

Tetrahedron ◽  
2013 ◽  
Vol 69 (41) ◽  
pp. 8680-8704 ◽  
Author(s):  
Stephen G. Davies ◽  
Emma M. Foster ◽  
James A. Lee ◽  
Paul M. Roberts ◽  
James E. Thomson
Keyword(s):  
Conjugate Addition ◽  
Addition Reactions ◽  
Asymmetric Syntheses ◽  
Lithium Amide

Thia-Michael Addition Reactions in Water Using 3-[Bis(Alkylthio) Methylene] Pentane-2,4-Diones as Odorless and Efficient Thiol Equivalents

2007 ◽  
Vol 4 (4) ◽  
pp. 281-284 ◽  
Author(s):  
Yanyan Chai ◽  
Dewen Dong ◽  
Yan Ouyang ◽  
Yongjiu Liang ◽  
Yan Wang ◽  
...  
Keyword(s):  
Michael Addition ◽  
Addition Reactions

Ionic dimerisation of trifluoropropenenitrile and its addition reactions with methyl trifluoropropenoate

1980 ◽  
Vol 45 (2) ◽  
pp. 406-414 ◽  
Author(s):  
Jiří Svoboda ◽  
Oldřich Paleta ◽  
Václav Dědek
Keyword(s):  
Reaction Mechanism ◽  
Proton Transfer ◽  
Substituent Effect ◽  
Solvent Molecule ◽  
Addition Product ◽  
Potassium Fluoride ◽  
Relative Reactivity ◽  
Addition Reactions ◽  
Tertiary Amines ◽  
Optimum Conditions

Dimerisation of trifluoropropenenitrile (I) in the presence of potassium fluoride and tertiary amines afforded a mixture of stereoisomeric perfluoro-4-methyl-pentenedinitriles (II), higher-boiling compounds, and 2,3,3,3-tetrafluoropropanenitrile (III) which arises by proton transfer from the solvent molecule. Under optimum conditions, product II was obtained in about 50% yield. Reaction of the nitrile I with methyl trifluoropropenoate (IV) gave, besides the dimers II and V, the product of addition of the nitrile I to the propenoate, IV, i.e. methyl 4-cyanoperfluoro-2-pentenoate (VI), and the addition product of the propenoate IV to the nitrile I, i.e. methyl 4-cyanoperfluoro-2-methyl-3-butenoate (VII). The relative reactivity if I and IV is discussed. The ratio of stereoisomers in II, V, VI and VII indicates that the magnitude of the steric substituent effect, operating in the reaction mechanism, decreases in the order -CFCF3.(COOCH3) > -CFCF3(CN) > -COOCH3 > -CN.

Relative Reactivities of 1,1,1-Trichloroethane and 1,1,1-Trichlorotrifluoroethane in Competitive Addition Reactions

1992 ◽  
Vol 57 (6) ◽  
pp. 1291-1298 ◽  
Author(s):  
František Adámek ◽  
Milan Hájek ◽  
Zbyněk Janoušek
Keyword(s):  
Free Radical ◽  
Reaction Mechanism ◽  
Relative Reactivity ◽  
Addition Reactions ◽  
Radical Initiation ◽  
Amine Complexes ◽  
Free Radical Initiation ◽  
Ru Complexes ◽  
Radical Initiators

Relative reactivity of CH3CCl3 and CF3CCl3 measured in competitive addition reactions with 1-hexene in the presence of free radical initiators or Cu, Pd and Ru complexes was found to depend on the type of catalyst. The unusual course of the reaction has been found in the additions catalyzed with copper(I)-amine complexes where CH3CCl3 in competition with CF3CCl3 was completely unreactive. The results have been explained in terms of the change of reaction mechanism and compared with classical free radical initiation.

scholarly journals Lithium-mediated Ferration of Fluoroarenes

2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia
Keyword(s):  
Hydrogen Atom ◽  
Organometallic Chemistry ◽  
Room Temperature ◽  
Structural Elucidation ◽  
Side Reactions ◽  
Metal Base ◽  
Lithium Amide ◽  
Mixed Metal ◽  
Important Challenge

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.

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