Conceptually new chiral tertiary C2 symmetric diamines in asymmetric synthesis

New chiral diamines were prepared, based on the cyclohexane diamine core. The two different substituents on each nitrogen allow this heteroatom to become a stereogenic center upon chelation with a metal, such as lithium. The enantioselective addition of MeLi to imines, with ee's up to 68%, illustrates the validity of this concept

Enantioselective addition of aryllithium reagents to aromatic imines mediated by 1,2-diamine ligands

A variety of optically enriched amines have been obtained by addition of aryllithium reagents to aromatic imines using N,N'-tetramethylcyclohexane-1,2-diamine as chiral ligands. Enantiomeric excesses up to 90% could be obtained

Enantioselective addition of MeLi to aromatic imines catalyzed by C2-symmetric tertiary diamine

Enantioselective addition of methyllithium to aromatic imines catalyzed by C2 symmetric tertiary diamines is described. Eleven diamines have been tested, for which dramatic effect of the nitrogen substitution has been observed. Diamines bearing hindered group close to the nitrogen led to racemic product while homologous hindered diamines led to the best results. Enantiomeric excess up to 74% could be achieved. An explanation of the absolute configuration of the product obtained is given considering the mechanism of the reaction

A new pseudo C2-symmetric tertiary diamine for the enantioselective addition of MeLi to aromatic imines

New tertiary pseudo C2-symmetric 1,2-diamine 2b was synthesized and compared to 1b in the enantioselective addition of MeLi to imines 3a–f. Comparable selectivity and better reactivity were observed with this novel diamine

alpha- and beta-Stannyl Trifluoromethylbutenoates: Regioselective Preparation and Use in Copper(I)-Catalyzed Allylation and Propargylation Reactions

International audienceThe palladium-free hydrostannylation of ethyl 4,4,4-trifluorobutynoate with tributyltin hydride at room temperature is highly regio- and stereoselective, providing good yields of beta-trifluoro- methyl (Z)-alpha- or (Z)-beta-stannylacrylates. Vinyl- stannanes undergo a copper(I)-catalyzed coupling reactions with allylic or propargylic bromides leading selectively to good yields of the corresponding allylated or propargylated products without allylic or allenic transposition

Apport du groupement CF3 à la réactivité du 4,4,4,-trifluorobutynoate d’éthyle. Application à la synthèse d’hétérocycles à visée antiparasitaire

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