A highly efficient asymmetric Mannich-type reaction between α-tetralone-derived β-keto esters/amides and 1,3,5-triaryl-1,3,5-triazinanes was realized in the presence of chiral N,N′-dioxide–Ni(II) or Mg(II) complex. A variety of optically active β-amino compounds with all-carbon quaternary stereocenters were obtained in good yields with excellent enantioselectivities. A possible transition state was
synergistic use of chiral bifunctional ammonium iodide catalysts in combination with simple catalytically relevant aldimines allows for an unprecedented asymmetric α-hydroxylation reaction of β-ketoesters using H2O2. The reaction proceeds via in situ formation of a hypervalent iodine species, which then reacts with the used aldimine to generate an activated electrophilic oxygen transfer reagent.
手性双官能碘化铵催化剂与简单的催化相关的醛亚胺的协同使用可实现前所未有的使用H 2 O 2的β-酮酸酯的不对称α-羟基化反应。该反应通过原位形成高价碘物质进行,然后与用过的醛亚胺反应生成活化的亲电子氧转移试剂。
Construction of Vicinal Quaternary Carbon Centers via Cobalt-Catalyzed Asymmetric Reverse Prenylation
作者:Minghe Sun、Jia-Feng Chen、Shufeng Chen、Changkun Li
DOI:10.1021/acs.orglett.8b04030
日期:2019.3.1
A highly enantioselective cobalt-catalyzed reverse prenylation of β-ketoester with tertiary allylic carbonate to construct vicinal all-carbon quaternarycarboncenters has been developed. By using the cobalt/(S,S)Ph-BPE complex generated in situ with zinc reduction, excellent branched to linear selectivity (>20:1) and up to 92% ee have been obtained.
Catalytic enantioselective chlorination of cyclic β-keto esters in the presence of chiral Pd(II) complexes
作者:Young Ku Kang、Hee Hun Kim、Kwang Oh Koh、Dae Young Kim
DOI:10.1016/j.tetlet.2012.05.064
日期:2012.7
The catalyticenantioselective electrophilic chlorination promoted by chiral palladium complexes is described. The treatment of β-keto esters with 2,3,4,5,6,6-hexachlorocyclohex-2,4-dienone as chlorine source under mild reaction conditions afforded the corresponding α-chlorinated β-keto esters with excellent enantioselectivities (up to 94% ee).
Asymmetric α‐Hydroxylation of Tetralone‐Derived β‐Ketoesters by Using a Guanidine–Urea Bifunctional Organocatalyst in the Presence of Cumene Hydroperoxide
Highly enantioselective catalytic oxidation of 1‐tetralone‐derivedβ‐keto esters was achieved by using a guanidine–ureabifunctionalorganocatalyst in the presence of cumenehydroperoxide (CHP), a safe, commercially available oxidant. The α‐hydroxylation products were obtained in 99 % yield with up to 95 % enantiomeric excess (ee). The present oxidation was successfully applied to synthesize a key