(and in some cases rhodium) catalysed regiospecific 5-exo-, 6-endo-and 6-exo-trig cyclisations of aryl iodides and vinyl bromides onto proximate alkenes or heteroaromatic rings (indole, pyrrole) lead to a wide variety of fusedring systems. In appropriate cases the methodology provides a facile approach to the creation of tetrasubstituted carbon centres. Double bond isomerisation in the product is only
six-membered benzo-fused N-, O-, and S-heterocycles is reported. The key step involves the generation of a benzyne-tethered vinyl or aryllithium compound that undergoes a subsequent intramolecular anionic cyclization. Reaction of the organolithium intermediates with selected electrophiles allows the preparation of a wide variety of indole, tetrahydrocarbazole, dihydrofenantridine, dibenzopyran, and dibenzothiopyran
derived from bis(2-bromoallyl)amines undergo intramolecular carbometallation of a lithiateddouble bond, giving dilithiated dihydropyrroles. The cyclizations are promoted by N,N,N',N'-tetramethylethylenediamine (TMEDA). Reaction of these intermediates with electrophiles allows the preparation of some new fused and nonfused five-membered functionalized heterocycles. Although 2-lithioallylamines do
Copper-Catalyzed Asymmetric Allylic Alkylation of Racemic Cyclic Substrates: Application of Dynamic Kinetic Asymmetric Transformation (DYKAT)
作者:Jean-Baptiste Langlois、Alexandre Alexakis
DOI:10.1002/adsc.200900790
日期:2010.2.15
The copper-catalyzedasymmetricallylicalkylation (AAA) is of great interest in organic synthesis. This reaction was extensively studied using a broad range of substrates, ligands and organometallic reagents. However, the use of racemic substrates was still limited. Although some processes of kinetic resolution are reported in the literature, no examples of quantitative deracemization are described
Silver Salt-Mediated Allylation Reactions Using Allyl Bromides
作者:Xiaodong Xiong、Jonathan Wong、Ying-Yeung Yeung
DOI:10.1021/acs.joc.1c00480
日期:2021.5.7
A facile, efficient, and chemoselective synthesis of allylic amides has been developed. Allyl bromides were used as the precursors activated by silver triflate. A Ritter-type reaction readily proceeded to give various allyl amides under mild conditions. The reaction protocol was also applicable to different nucleophilic partners to give a wide range of allyl-substituted products in the absence of a