highly enantioselective insertion of α-aryl-α-diazoacetates into the O–H bonds of phenols has been successfully developed by employing palladium/2,2′-biimidazole complexes as catalysts, furnishing the chiral α-aryl-α-aryloxyacetates with up to 98% ee and 97% yield. Furthermore, these chiral palladium/2,2′-biimidazole complexes have also exhibited a good performance in the asymmetric insertion of α-aryl-α-diazoacetates
Stereoselective Synthesis of Difluorinated 1,3-Dienes via Palladium-Catalyzed C–F Bond Activation of Tetrasubstituted <i>gem</i>-Difluoroalkenes
作者:Yanhui Wang、Qiao Ma、Gavin Chit Tsui
DOI:10.1021/acs.orglett.1c01768
日期:2021.7.2
Pd(0)-catalyzed synthesis of difluorinated 1,3-dienes is described. Symmetrical 1,3-dienes containing a vicinal difluoro moiety can be obtained as single diastereomers from tetrasubstituted gem-difluoroalkenes. The reaction presumably proceeds through a stereoselective twofold Pd-catalyzed Miyaura borylation/Suzuki–Miyaura cross-coupling of the C–F bond. Moreover, modular synthesis of unsymmetrical
C(sp2)–H Bond Multiple Functionalization in Air for Construction of Tetrahydrocarbazoles with Continuous Quaternary Carbons and Polycyclic Diversification
作者:Longlong Song、Dan Ni、Shikun Jia、Rou Pi、Suzhen Dong、Fan Yang、Jie Tang、Shunying Liu
DOI:10.1021/acs.orglett.0c00145
日期:2020.3.6
The C(sp2)-H function of indole ketone with diazo compound via a rhodium(II)-catalyzed intramolecular electrophilic trapping reaction under mild conditions in air was demonstrated. The established methodology provided a highly efficient approach for direct synthesis of mutisubstituted tetrahydrocarbazoles with continuous quaternary carbons. The resulting products facilitate further modification to
Preparation of Axially Chiral 2,2′-Biimidazole Ligands through Remote Chirality Delivery and Their Application in Asymmetric Carbene Insertion into N–H of Carbazoles
Axially chiral biimidazole ligands have been rarely synthesized and studied, in contrast to the significant achievements in the synthesis and application of central chiral imidazole ligands. Herein, a series of novel axially chiral2,2′-biimidazole ligands were synthesized from the reaction of 2,2′-bis(bromomethyl)-1,1′-binaphthalene and 2,2′-biimidazole in one step through the strategy of remote chirality
visible-light-mediated formal carbene insertion reaction of 1,3-diketones with diazoesters for the construction of enantioenriched 1,4-dicarbonyl compounds with a quaternary carbon center. Combining visible light and a Brønsted acid catalyst, chiral 1,4-dicarbonyl compounds were achieved in good yields with high enantioselectivities by a photochemical carbene transfer protocol.