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 … WebSep 27, 2024 · Chiral lithium amide bases allow the desymmetrisation of prochiral substrates and the production of enantiomerically enriched products, which are vital for …
The diamine (-)-sparteine and three chiral lithium amide bases.
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 ... 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 … tryhard xbox usernames
Enantioselective deprotonation by chiral lithium amide …
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 ... WebChiral 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] . Chiral lithium amides may be used to effect the selective removal of one of two enantioselective protons in prochiral substrates. In the vast majority of cases, high enantioselection depends on the presence of a coordinating heteroatom in the prochiral substrate. Coordination between lithium and the … See more Provided the substrate is not sensitive to strong base and contains an appropriately positioned coordinating group, the scope of reactions of chiral lithium amides is quite wide. This … See more A number of alternative reagents for enantioselective deprotonation and functionalization are known. For example, chiral magnesium … See more Enantioselective deprotonations are typically employed in the early stages of synthesis, when starting materials are unlikely to be sensitive to base. Despite the requirement of … See more try hardy