Synthesis of chiral spirocyclic ketones was accomplishedviathe Pd-catalyzed intramolecular α-arylation of α-substituted cyclic ketones. The obtained spirocyclic ketone could be converted into an acid–base organocatalyst.
We herein report the development of a sterically hindered and electron-rich P-chiral monophosphorus biaryl ligand that has enabled a general and efficient enantioselective intramolecular alpha-arylation, providing access to a wide series of [4.4], [4.5], and [4.6]-spirocycles with chiral benzylic quaternary carbons in high yields with good to excellent enantioselectivities. A pronounced water effect on enantioselectivity is observed.
Palladium-catalyzed intramolecular α-arylation of aliphatic ketone, formyl, and nitro groups
Intramolecular arylation of properly designed substrates bearing a ketone, formyl, or nitro terminating group was achieved by use of a PdCl2(Ph3P)2–Cs2CO3 reaction system to form a variety of carbocyclic compounds. Arylation in ketone compounds afforded benzene-annulated bridged or spirocycloalkanone derivatives, depending on the structure of the cyclization precursors. Arylation in formyl compounds
通过使用PdCl 2(Ph 3 P)2 -Cs 2 CO 3,对设计适当的带有酮,甲酰基或硝基终止基团的底物进行分子内芳构化反应体系形成各种碳环化合物。取决于环化前体的结构,酮化合物中的芳基化可提供苯环化的桥环或螺环烷酮衍生物。取决于环化前体的结构和反应溶剂,甲酰基化合物中的芳基化发生在α位置(α-芳基化)或羰基碳(羰基芳基化)。α-芳基化的仲硝基以Nef反应的方式部分转化为酮,而叔硝基被部分消除,得到苯乙烯型烯烃。