Chiral lithium amide

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Lithium amide or lithium azanide is an inorganic compound with the chemical formula LiNH2. It is a white solid with a tetragonal crystal structure. Lithium amide can be made by treating lithium metal with liquid ammonia: 2 Li + 2 NH3 → 2 LiNH2 + H2 WebLithium-hydrogen interchange between achiral tridentate lithium amides and chiral bidentate amines. An approach to catalytic enantioselective deprotonation. Tetrahedron …

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WebAn efficient enantioselective alkylation reaction at the α-position of cyclic ketones () can be realized in up to 92% enantiometric excess (e.e.) by first forming their lithium enolates using a chiral lithium amide in the presence of lithium bromide, followed by … WebFeb 14, 2014 · The structures, in THF, of 1:1 mixed aggregates of phenyllithium or vinyllithium with a chiral lithium amide derived from a 3-aminopyrrolidine are proposed … inch mm 変換表

Synthesis of Solid-phase Supported Chiral Amines and …

WebSince Whitesell[1] successfully applied a chiral lithium amide to enantioselective epoxide opening in 1980, the chemistry of chiral lithium amides has been greatly extended. … WebOct 24, 2012 · Experiments involving competition between chiral and achiral lithium amides provide a qualitative impression of the kinetics of different amide motifs in … WebJul 22, 1999 · The structure, dynamics, reactivity, and selectivity of mixed dimers (see equation) formed from the chiral lithium amides and alkyllithium reagents have been … income tax kya hota hai

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Solid-phase supported chiral lithium amides used in …

WebThese results suggest that the lithium amide derived from (241) is a more effective chiral auxiliary than the amine itself. In fact, if the reaction is carried out with excess n -butyllithium, along with a corresponding amount of the achiral diisopropylamine, the yield is excellent and the diastereomeric excess is a very respectable 68% ( Table ... WebJul 22, 1997 · We have shown by the use of multinuclear and multidimensional NMR that the reaction mixture of [6Li]lithium (2-methoxy-(R)-1-phenylethyl)((S)-1-phenylethyl)amide (2) and cyclohexene oxide in DEE results in the formation of monomeric and dimeric complexes between 2 and cyclohexene oxide at −80 °C. The dimeric complex of 2 exhibited a slow … income tax landlordWebThe use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines. Chiral base desymmetrisation of dimethyl sulfoximines could provide a … income tax ky

"WebAn enantioselective Meerwein-Ponndorf-Verley-type reduction of ynenoylsilanes by a chiral lithium amide followed by a Brook rearrangement and anti-mode protonation across conjugated 1,3-enynes provides allene derivatives bearing a 2-siloxyvinyl moiety in high enantioselectivity. The E/Z geometry of enol silyl ethers is controlled by the geometry of … " - Chiral lithium amide

Chiral lithium amide

WebChiral auxiliaries are one of many strategies available to synthetic chemists to selectively produce the desired stereoisomer of a given compound. ... Treatment of this compound … WebThe use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines. Chiral base desymmetrisation of dimethyl sulfoximines could provide a general route to chiral ...

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WebSeven selected chiral mono-, di-, and tridentate amines supported on insoluble polymer were effectively prepared from corresponding primary amines or secondary amino alcohols and Merrifield resin. The reaction of the polymer-supported amines with excess n-butyllithium gave the corresponding lithium amide bases, which were tested in the aldol … WebAug 16, 2007 · Deprotonation with lithium amide (R,R)-5 in the presence of lithium chloride (conveniently generated in situ by deprotonation of the amine hydrochloride with …

WebFeb 1, 2007 · A novel type of chiral lithium amide base reaction, involving the rearrangement of certain types of symmetrical ring-fused episulfoxides, gives alkenyl sulfoxide products in up to 88% ee. WebA direct, highly enantioselective alkylation of arylacetic acids via enediolates using a readily available chiral lithium amide as a stereodirecting reagent has been developed. This approach circumvents the traditional attachment and removal of chiral auxiliaries used currently for this type of transformation. The protocol is operationally simple, and the …

WebMay 16, 2003 · The chiral lithium amide bases lacking internal coordinating groups show a very different behavior. In solution, these bases form several different types of aggregates such as ladders, dimers, trimers, etc. resulting in a reagent exhibiting low selectivity and reactivity. However, in the polymer supported case we define only one type of ... WebChiral enantioenriched organolithiums could also be prepared by deprotonation of prochiral substrates either using a chiral lithium amide or an alkyllithium in the presence of a chiral ligand. The deprotonation tactic is also useful for lithiation of aromatic rings at a proximal (or remote) site with respect to a “Directing Metalation Group ...

WebThe stereoselective synthesis of terminal bromo-substituted propargylamines via in situ generation of lithium bromoacetylide from …

WebMay 13, 2013 · 1. Introduction. The dimethyl ether of (R,R)- and (S,S)-1,2-dihydroxy-1,2-diphenylethane 1 is a powerful and widely applicable chiral external ligand 1 for asymmetric reactions of lithiated reagents, such as organolithium, 2 lithium enolate, and lithium amide. 3 Since the first report on the utility of chiral diether 1 in the catalytic and stoichiometric … inch mm 変換 googleWebJun 3, 2002 · The lithium amide 4a was chosen as chiral lithium amide in the calculations since this lithium amide is the smallest amongst the investigated amides that still results in good selectivity. We used dimethyl ether as the solvent. There are several possible conformers of the ground state structure according to the PM3 calculations, considering … inch mlWebJul 17, 1998 · The first demonstration of enantioselective ortho-lithiation of a monosubstituted ferrocene utilised the chiral lithium amide 95. Although this was insufficiently basic to deprotonate a wide range of functionalised ferrocenes, and gave racemic products from a sulfone and a diisopropylcarboxamide, the phosphine oxide 94 … inch miter sawWebChiral auxiliaries, in the form of esters of chiral alcohols and amides of C 2-symmetric chiral amines have been evaluated in these rearrangements. For example, Nakai showed that the lithium enolates of 8-phenylmenthol esters afford good simple diastereoselectivity with good asymmetric induction as well ( Scheme 6.59 , [340] . inch mm 換算WebRecent advances in asymmetric synthesis using chiral lithium amide bases . Peter O’Brien Abstract. Covering: January 1991 to September 1997 inch mm cm conversion chartWebEnantiopure synthesis. Enantiopure tert-butanesulfinamide can be prepared by enantioselective oxidation of inexpensive di-tert-butyl disulfide to the thiosulfinate followed by disulfide bond cleavage by lithium amide.In the original scope the chiral ligand used together with vanadyl acetylacetonate was prepared by condensing an optically pure … income tax laredo texasWebSince Whitesell[1] successfully applied a chiral lithium amide to enantioselective epoxide opening in 1980, the chemistry of chiral lithium amides has been greatly extended. During the following 27 years, more and more studies have been focusing on the deprotonation reactions of ketones and also on the enolate chemistry. Many income tax last date for filing