N-Heterocyclic Carbene-Catalyzed [3 + 2] Annulation of 3,3'-Bisoxindoles with α-Bromoenals: Enantioselective Construction of Contiguous Quaternary Stereocenters.
Sign Up to like & getrecommendations! Published in 2022 at "Organic letters"
DOI: 10.1021/acs.orglett.2c02180
Abstract: An NHC-catalyzed enantio- and diastereoselective [3 + 2] annulation of α-bromoenals with bisoxindoles is developed, affording efficient access to various spirocyclic bisoxindole alkaloids. This protocol tolerates a broad substrates scope, with various spirocyclic bisoxindoles obtained… read more here.
Keywords: quaternary stereocenters; catalyzed annulation; annulation; annulation bisoxindoles ... See more keywords
Generation and [2,3]-Sigmatropic Rearrangement of Ammonium Ylides from Cyclopropyl Ketones for Chiral Indolizidines with Bridgehead Quaternary Stereocenters.
Sign Up to like & getrecommendations! Published in 2022 at "Organic letters"
DOI: 10.1021/acs.orglett.2c02759
Abstract: A sequence of nucleophilic ring opening of cyclopropyl ketones, N-quaternization, deprotonation, and [2,3]-sigmatropic rearrangement of ammonium ylides has been developed. This method enables efficient synthesis of bicyclic indolizidines bearing bridgehead aza-quaternary stereocenters from easily available… read more here.
Keywords: quaternary stereocenters; rearrangement ammonium; cyclopropyl ketones; ammonium ylides ... See more keywords
Stereoselective Electrophilic α-Alkynylation of α,α-Disubstituted N-tert-Butanesulfinyl Ketimines for Construction of Less Accessible Acyclic Quaternary Stereocenters.
Sign Up to like & getrecommendations! Published in 2022 at "Organic letters"
DOI: 10.1021/acs.orglett.2c03865
Abstract: In order to construct less accessible acyclic quaternary stereocenters, a protocol was developed to α-alkynylate α,α-disubstituted N-tert-butanesulfinyl ketimines stereoselectively using 1-(2-trimethylsilylethynyl)-1,2-benziodoxol-3(1H)-one in the presence of fluoride. Despite the steric and electrical similarity between the two… read more here.
Keywords: quaternary stereocenters; disubstituted tert; alkynylation; less accessible ... See more keywords
Fe-Catalyzed Alkylazidation of α-Trifluoromethylalkenes: An Access to Quaternary Stereocenters Containing CF3 and N3 Groups.
Sign Up to like & getrecommendations! Published in 2023 at "Organic letters"
DOI: 10.1021/acs.orglett.3c00439
Abstract: A concise Fe-catalyzed alkylazidation of α-trifluoromethylalkenes via a C-C bond cleavage/radical addition/azidation cascade is described. This protocol features a broad substrate scope, excellent functional group compatibility, and the ability to be performed on a gram… read more here.
Keywords: quaternary stereocenters; trifluoromethylalkenes access; catalyzed alkylazidation; alkylazidation trifluoromethylalkenes ... See more keywords
Tuning the Reactivity of Ketones through Unsaturation: Construction of Cyclic and Acyclic Quaternary Stereocenters via Zn-ProPhenol Catalyzed Mannich Reactions
Sign Up to like & getrecommendations! Published in 2019 at "ACS Catalysis"
DOI: 10.1021/acscatal.8b04685
Abstract: Introduction of unsaturation adjacent to the carbonyl drastically improves the reactivity of the Zn-ProPhenol catalyzed Mannich reactions between N-carbamoyl imines and a-branched ketones. Despite only a small change in the substrate acidity, the bimetallic catalyst… read more here.
Keywords: cyclic acyclic; acyclic quaternary; catalyzed mannich; quaternary stereocenters ... See more keywords
Organo-Cation Catalyzed Asymmetric Homo/Heterodialkylation of Bisoxindoles: Construction of Vicinal All-Carbon Quaternary Stereocenters and Total Synthesis of (-)-Chimonanthidine.
Sign Up to like & getrecommendations! Published in 2018 at "Journal of the American Chemical Society"
DOI: 10.1021/jacs.8b05386
Abstract: A novel chiral spirocyclic amide (SPA)-derived triazolium organocatalyst has been designed and demonstrated to effect asymmetric homo- and heterodialkylations of various bisoxindoles, enabling enantioselective construction of vicinal all-carbon quaternary stereocenters. These reactions feature excellent enantio-… read more here.
Keywords: carbon quaternary; quaternary stereocenters; vicinal carbon; total synthesis ... See more keywords
Construction of All-Carbon Quaternary Stereocenters by Scandium-Catalyzed Intramolecular C-H Alkylation of Imidazoles with 1,1-Disubstituted Alkenes.
Sign Up to like & getrecommendations! Published in 2020 at "Journal of the American Chemical Society"
DOI: 10.1021/jacs.9b12503
Abstract: The exo-selective C-H cycloaddition of imidazoles to 1,1-disubstituted alkenes has been achieved for the first time by using half-sandwich scandium catalysts. A wide range of imidazole compounds bearing various 1,1-disubstituted aliphatic alkenes, styrenes, dienes and… read more here.
Keywords: construction carbon; carbon quaternary; quaternary stereocenters; imidazoles disubstituted ... See more keywords
An enantioselective cascade for simultaneous generation of five quaternary stereocenters from fully substituted enones.
Sign Up to like & getrecommendations! Published in 2017 at "Chemical communications"
DOI: 10.1039/c7cc03995f
Abstract: A highly enantioselective cascade reaction for the generation of five quaternary stereocenters in one-pot operation is reported for the first time in the history of organic synthesis. Cinchona-alkaloid derived hydrogen-bonding catalyst furnished structurally complex cascade… read more here.
Keywords: quaternary stereocenters; five quaternary; cascade simultaneous; generation five ... See more keywords
Cross-dehydrogenative coupling enables enantioselective access to CF3-substituted all-carbon quaternary stereocenters†
Sign Up to like & getrecommendations! Published in 2020 at "Chemical Science"
DOI: 10.1039/c9sc05894j
Abstract: A cross-dehydrogenative coupling strategy for enantioselective access to acyclic CF3-substituted all-carbon quaternary stereocenters has been established. By using catalytic DDQ with MnO2 as an inexpensive terminal oxidant, asymmetric cross coupling of racemic δ-CF3-substituted phenols with… read more here.
Keywords: quaternary stereocenters; cf3 substituted; cross dehydrogenative; carbon quaternary ... See more keywords
Enantioselective construction of triaryl-substituted all-carbon quaternary stereocenters via organocatalytic arylation of oxindoles with azonaphthalenes
Sign Up to like & getrecommendations! Published in 2023 at "Chemical Science"
DOI: 10.1039/d2sc07103g
Abstract: Azonaphthalenes have been verified as a class of effective arylation reagents in a variety of asymmetric transformations. Here a highly efficient approach to construct triaryl-substituted all-carbon quaternary stereocenters through chiral phosphoric acid-catalyzed enantioselective arylation of… read more here.
Keywords: quaternary stereocenters; triaryl substituted; carbon quaternary; substituted carbon ... See more keywords
Samarium Diiodide Catalyzed Radical Cascade Cyclizations that Construct Quaternary Stereocenters
Sign Up to like & getrecommendations! Published in 2019 at "Synlett"
DOI: 10.1055/s-0039-1690196
Abstract: SmI2-catalyzed radical cascade cyclizations were used to generate complex carbocyclic products bearing quaternary stereocenters with high selectivity. Bicyclic scaffolds containing four contiguous stereocenters and one quaternary stereocenter were obtained in excellent yields (up to 99%)… read more here.
Keywords: radical cascade; cascade cyclizations; quaternary stereocenters; catalyzed radical ... See more keywords