Lithiated β-aminoalkyl sulfones as mono and dinucleophiles in the preparation of nitrogen heterocycles: Application to the synthesis of capsazepine
作者:Diego A. Alonso、Ana Costa、Balbino Mancheño、Carmen Nájera
DOI:10.1016/s0040-4020(97)00163-4
日期:1997.3
lithiation of N-benzyl-β-tosylethanamine (10a) and N-benzyl-α-phenyl-β-tosylethanamine (10b) with n-butyllithium at −78°C leads to monoanions 11a and 11b, respectively. Intermediates 11 react with different monoelectrophiles (D2O, alkyl halides, and carbonyl compounds) at the α-position with respect to the sulfone, and with dielectrophiles (1,3-, 1,4-dihalides, α-bromoacetates, and α-chloroketones) to afford
and convenient synthesis of α‐allyl cyclic amidines has been achieved by applying a novel cascade reaction. Copper(I)‐mediated in situ N‐sulfonyl ketenimine formation from the reaction of a terminal alkyne with sulfonyl azide is followed by an intramolecular nucleophilic attack on the central carbon atom by an allylic tertiary amine, and then an aza‐Claisen rearrangement takes place through a chair
A new phosphoramiditeligand was used in the iridium-catalyzed allylicsubstitution reaction. This permitted high regio- and enantioselectivities on a wide variety of substrates and nucleophiles. Because of the stereospecificity of the reaction obtained by using branched substrates, a kinetic resolution reaction was attempted. The origin of the impressive efficiency of this ligand in terms of kinetics
Regio- and Enantioselective Allylic Amination of Achiral Allylic Esters Catalyzed by an Iridium−Phosphoramidite Complex
作者:Toshimichi Ohmura、John F. Hartwig
DOI:10.1021/ja028614m
日期:2002.12.1
asymmetric process, the iridium-catalyzedenantioselectiveallylicamination of (E)-cinnamyl and terminal aliphatic allylic carbonates, was developed by exploring complexes of chiral phosphoramidites. The reaction provided branched secondary and tertiary allylic amines in high yields with excellent regio- and enantioselectivity (13 examples over 94% ee). Although the reactions in polar solvent such as
A domino process involving Michael addition and carbocyclization has been developed starting from beta-N-allylamino enoates and various organometallic reagents (organozinc halides, diorganozinc reagents, and copper/zinc mixed species). In all cases the mechanism of this dominoreaction has been evidenced to involve a radical-polarcrossover mechanism.