Enantioselective C−C Bond Cleavage Creating Chiral Quaternary Carbon Centers
摘要:
A chiral all-carbon benzylic quaternary carbon center is created by the asymmetric intramolecular addition/ring-opening reaction of a borylsubstituted cyclobutanone, which involves enantioselective ss-carbon elimination from a symmetrical rhodium cyclobutanolate. The asymmetric reaction was successfully applied to a synthesis of sesquiterpene, (-)-alpha-herbertenol.
Enantioselective C−C Bond Cleavage Creating Chiral Quaternary Carbon Centers
摘要:
A chiral all-carbon benzylic quaternary carbon center is created by the asymmetric intramolecular addition/ring-opening reaction of a borylsubstituted cyclobutanone, which involves enantioselective ss-carbon elimination from a symmetrical rhodium cyclobutanolate. The asymmetric reaction was successfully applied to a synthesis of sesquiterpene, (-)-alpha-herbertenol.
A palladium‐catalyzed enantioselective sequential ring‐opening/cross‐coupling of cyclobutanones is disclosed that provides chiral indanones bearing C3‐quaternary stereocenters. The reaction process involves palladium‐catalyzed nucleophilic addition of cyclobutanones and aryl halides, enantioselective β‐carbon elimination, and intermolecular trapping of a transient σ‐alkylpalladium complex with boronic
Catalytic C–C Cleavage/Alkyne–Carbonyl Metathesis Sequence of Cyclobutanones
作者:Jiqiang Gao、Chunhui Liu、Zhongjuan Li、Haotian Liang、Yuhui Ao、Jinbo Zhao、Yuchao Wang、Yuanqi Wu、Yu Liu
DOI:10.1021/acs.orglett.0c01317
日期:2020.5.15
substrates decorated with various substituents at different positions were all well accommodated. Preliminary mechanistic studies show that silver salt acted as a Lewis acid to facilitate both C-C cleavage of the cyclobutanone moiety and the subsequent metathesis between C═O and C≡C bonds.
A palladium‐catalyzedenantioselective intramolecular σ‐bond cross‐exchange between C−I and C−C bonds is realized, providing chiral indanones bearing an alkyl iodide group and an all‐carbon quaternarystereocenter. Pd/TADDOL‐derived phosphoramidite is found to be an efficient catalytic system for both C−C bond cleavage and alkyl iodide reductive elimination. In addition to aryl iodides, aryl bromides
Transition-metal catalyzed C—Cbond activation is a formidable challenge owing to the high bond energy. We report here a novel palladium-catalyzed C—Cbond activation manner of methylenecyclobutanes followed by subsequent Suzuki cross-coupling reaction affording multisubstituted indanes. The tandem reaction process involves intramolecular carbopalladation of double bond, β-carbon elimination and intermolecular
functionalization of carbon–carbon σ bonds is a synthetic strategy that offers uncommon retrosynthetic disconnections. Despite progress in CCactivation and its great importance, the development of asymmetric reactions lags behind. Rhodium(I)‐catalyzed selective oxidative additions into enantiotopicCCbonds in cyclobutanones are reported. Even operating at a reaction temperature of 130 °C, the process is characterized