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1.
A Rh(I)/(R)-Tol-BINAP catalyst reacts with a racemic mixture of 4-alkynals to selectively furnish a cyclobutanone from the (R)-substrate and a cyclopentenone from the (S)-substrate. This method is noteworthy from several standpoints, including the scarcity of parallel kinetic resolutions (especially those that are catalyzed or that involve carbon-carbon bond formation) and the dearth of catalytic processes that generate enantioenriched cyclobutanones. 相似文献
2.
3-(2-Hydroxyphenyl)cyclobutanones react with aryl bromides in the presence of palladium catalysts to afford 4-arylmethyl-3,4-dihydrocoumarins in high yields through a sequence involving carbon-carbon bond cleavage and formation. In the case of the reaction with 2-(2-hydroxyphenyl)cyclobutanones, five- or seven-membered lactones were produced depending on the presence of an additional substituent at the 2-position. 相似文献
3.
γ-Lactone-cis-annulation to Δ2- and Δ3- Cholestene. From Δ2- and Δ3- cholestene the γ-lactones 11a , 11b , 12a , and 12b are synthesized through the dibromocarbene adducts 3 and 4 , the bromohydrines 5 and 6 , the oxapiropentanes 7 and 8 , and the cyclobutanones 9a , 9b and 10a , 10b , respectively. The 13C-NMR.-spectra of 1–8 and 11 as well as the ORD.-spectra of the cyclobutanones 9 and 10 are reported. 相似文献
4.
《中国化学》2018,36(7):612-618
Chiral β‐lactams and cyclobutanones are present in numerous natural and pharmaceutical products. The stereoselective construction of chiral four‐membered cyclic compounds is an ongoing challenge for the chemical community. Herein, we report a highly stereocontrolled construction of four‐membered ring (mini‐sized) β‐lactams and cyclobutanones via an Ir/ In‐BiphPHOX ‐catalyzed asymmetric hydrogenation, providing the corresponding optically active four‐membered ring carbonyl products bearing an α‐chiral carbon center with excellent yields (up to 99%) and enantioselectivities (up to 98%) under mild reaction conditions (1.0—2.5 bar H2 for 1.0—10 h). The reaction presents wide substrate scope. Diverse transformations of the catalyzed products were also conducted to show the potential utility of this protocol. 相似文献
5.
Jian Cao Ling Chen Feng‐Na Sun Yu‐Li Sun Ke‐Zhi Jiang Ke‐Fang Yang Zheng Xu Li‐Wen Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(3):907-911
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 acids. Alternatively, an intramolecular cyclopropanation is realized through C?H bond functionalization in the absence of external coupling reagents, affording chiral cyclopropane‐fused‐indanones in good yields and enantioselectivity. 相似文献
6.
A method for the enantioselective synthesis of γ-lactones through the reaction of enantioenriched sulfoxonium ylides, aldehydes, and ketenes was developed. Enantioenriched (98% ee) aminosulfoxonium ylide was subjected to reaction with a variety of aldehydes (both aromatic and aliphatic) and disubstituted ketenes, leading to the formation of α,β-substituted γ-lactones in moderate to very good diastereoselectivity (dr up to 95:5) and with enantiomeric excesses of up to 79% ee. Best levels of enantioselectivity were observed in the reactions of enantioenriched aminosulfoxonium ylide with isobutyraldehyde and various alkylarylketenes. 相似文献
7.
Dr. Zhitong Zheng Dr. Youliang Wang Xu Ma Dr. Yuxue Li Prof. Dr. Liming Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(40):17551-17555
Cyclobutanones are synthetically versatile compounds that often require extensive effort to access. Herein, we report a facile synthesis of cyclobutanones based on the C(sp3)−H insertion chemistry of oxidatively generated gold carbenes. Various cyclobutanones were obtained in synthetically useful yields from substrates with minimal structural prefunctionalization. This discovery reveals new synthetic utilities of gold-catalyzed oxidative transformations of alkynones. 相似文献
8.
Zhitong Zheng Youliang Wang Xu Ma Yuxue Li Liming Zhang 《Angewandte Chemie (International ed. in English)》2020,59(40):17398-17402
Cyclobutanones are synthetically versatile compounds that often require extensive effort to access. Herein, we report a facile synthesis of cyclobutanones based on the C(sp3)?H insertion chemistry of oxidatively generated gold carbenes. Various cyclobutanones were obtained in synthetically useful yields from substrates with minimal structural prefunctionalization. This discovery reveals new synthetic utilities of gold‐catalyzed oxidative transformations of alkynones. 相似文献
9.
Catalytic Asymmetric Dearomatization of Indolyl Dihydropyridines through an Enamine Isomerization/Spirocyclization/Transfer Hydrogenation Sequence
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Zi‐Lei Xia Prof. Dr. Chao Zheng Dr. Shou‐Guo Wang Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2018,57(10):2653-2656
A highly efficient synthesis of enantioenriched spiroindolines by catalytic asymmetric dearomatization of indolyl dihydropyridines through a chiral phosphoric acid catalyzed enamine isomerization/spirocyclization/transfer hydrogenation sequence has been developed. This reaction proceeds under mild reaction conditions, affording novel spiroindolines in good yields (up to 88 %) with excellent enantioselectivity (up to 97 % ee). DFT calculations provide insights into the reaction mechanism as well as the origin of stereochemistry. 相似文献
10.
Angela M BernardAngelo Frongia Francesco SecciGiovanna Delogu Jean OllivierPier P Piras Jacques Salaün 《Tetrahedron》2003,59(47):9433-9440
Mixtures of (E and Z)-2-cyclobutylidenepropyl sulfonates, readily available from α,α-disubstituted cyclobutanones arising from suitable cyclopropane derivatives ring expansion, underwent regioselective and stereospecific reduction by formate anion to offer, through π-1,1-trimethyleneallylpalladium complexes formed upon treatment with palladium(0), a new and convenient entry to the diastereomeric four-membered ring monoterpenoids (±)-fragranol and (±)-grandisol. 相似文献
11.
A facile and efficient enantioselective bromoaminocyclization of unsaturated sulfonamides has been developed using an amino-thiocarbamate catalyst. A range of enantioenriched pyrrolidines were prepared with up to 99% yield and 99% ee. The corresponding lactams could be obtained through oxidation of the pyrrolidines. 相似文献
12.
The biradical intermediate which results from the thermal ring fission of alkylidene cyclobutanones serves as a common precursor of isomerised cyclobutanones (1,3 carbon shift), and of dienones by way of intramolecular 1,5 hydrogen shift. 相似文献
13.
Andrea Cataffo Dr. Miguel Peña-López Riccardo Pedrazzani Antonio M. Echavarren 《Angewandte Chemie (International ed. in English)》2023,62(49):e202312874
Two different classes of stereoselective cyclizations have been developed using a chiral auxiliary approach with commercially available [JohnPhosAu(MeCN)SbF6] as catalyst. First, a stereoselective cascade cyclization of 1,5-enynes was achieved using the Oppolzer camphorsultam as chiral auxiliary. In this case, a one-pot cyclization-hydrolysis sequence was developed to directly afford enantioenriched spirocyclic ketones. Then, the stereoselective alkoxycyclization of 1,6-enynes was mediated by an Evans-type oxazolidinone. A reduction-hydrolysis sequence was selected to remove the auxiliary to give enantioenriched β-tetralones. DFT studies confirmed that the steric clash between the chiral auxiliary and alkene accounts for the experimentally observed diastereoselective cyclization through the Si face. 相似文献
14.
Aurapat Ngamnithiporn Toshihiko Iwayama Michael D. Bartberger Brian M. Stoltz 《Chemical science》2020,11(40):11068
The development of a palladium-catalyzed enantioselective decarboxylative allylic alkylation of cyclic siloxyketones to produce enantioenriched silicon-tethered heterocycles is reported. The reaction proceeds smoothly to provide products bearing a quaternary stereocenter in excellent yields (up to 91% yield) with high levels of enantioselectivity (up to 94% ee). We further utilized the unique reactivity of the siloxy functionality to access chiral, highly oxygenated acyclic quaternary building blocks. In addition, we subsequently demonstrated the utility of these compounds through the synthesis of a lactone bearing vicinal quaternary-trisubstituted stereocenters.The development of a palladium-catalyzed enantioselective decarboxylative allylic alkylation of cyclic siloxyketones to produce enantioenriched silicon-tethered heterocycles is reported. 相似文献
15.
Yong‐Bin Wang Quan‐Hao Wu Zhi‐Peng Zhou Shao‐Hua Xiang Yuan Cui Peiyuan Yu Bin Tan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13577-13581
Axially chiral 2‐arylpyrrole frameworks are efficiently accessed through a direct chirality transfer strategy by rapid cyclization of enantioenriched atropisomeric alkenes, which are generated by organocatalytic asymmetric N‐alkylation reactions. This approach accommodates a broad scope of substrates with remarkably high chirality transfer efficiency, affording novel atropisomers with a fully substituted pyrrole moiety and high enantiopurities. Given the enantioenriched atropisomeric alkenes, novel heterocyclic 2‐arylazepine atropisomers were realized through a rationally designed ene reaction. 相似文献
16.
《Tetrahedron》2019,75(23):3063-3079
The -CHF2 moiety has shown a growing interest in pharmaceutical and agrochemical applications over the last few years. Its introduction is therefore a current research topic for organic chemists. Several groups have reported the synthesis of difluoromethylated compounds. However, the more challenging enantioselective introduction of the difluoromethyl group has been scarcely described yet. We recently developed a new strategy, based on the use of an enantiopure difluoromethyl sulfoxide used as chiral and traceless auxiliary, for the synthesis of highly enantioenriched α-difluoromethyl alcohols. The first method developed in our laboratory aims to access highly stereoenriched α,α-difluoro-β-hydroxysulfoxides through the condensation of the enantiopure difluoromethyl sulfoxide on carbonyl derivatives. It is noteworthy that highly diastereo- and enantioenriched α,α-difluoro-β-hydroxysulfoxides can also be accessed after the diastereoselective reduction of highly enantioenriched α,α-difluoro-β-ketosulfoxides. Finally, the expected difluoromethyl-substituted alcohols can be obtained after removal of the chiral auxiliary with complete retention of stereoenrichment at carbon. 相似文献
17.
[reaction: see text] We have established an enantioselective synthesis of both C2 symmetric and unsymmetric tetra-ortho-substituted axially chiral biaryls through rhodium-catalyzed double [2 + 2 + 2] cycloaddition (up to >99% ee). This method serves as an attractive new route to enantioenriched tetra-ortho-substituted axially chiral biaryls in view of the one-step access to substrate diynes and tetraynes starting from readily available alkynes. 相似文献
18.
Malkov AV Friscourt F Bell M Swarbrick ME Kocovský P 《The Journal of organic chemistry》2008,73(11):3996-4003
Asymmetric Baeyer-Villiger reaction of symmetrical cyclobutanones 1a-j with urea-hydrogen peroxide (UHP) can be catalyzed by a complex of Pd(II) and the new terpene-derived P, N-ligand 7. The resulting lactones 2a-j were obtained in high yields and with good enantioselectivity (< or =81% ee). 相似文献
19.
Aitken DJ Bernard AM Capitta F Frongia A Guillot R Ollivier J Piras PP Secci F Spiga M 《Organic & biomolecular chemistry》2012,10(26):5045-5048
N-Phenylsulfonyl (S)-proline catalyzes the direct aldol reaction of 3-substituted cyclobutanones and aryl aldehydes in good yield and with excellent diastereoselectivity and enantioselectivity. This desymmetrization process provides highly functionalized cyclobutanones with control over three contiguous stereogenic centers. 相似文献
20.
Jan Sietmann Johannes M. Wiest 《Angewandte Chemie (International ed. in English)》2020,59(18):6964-6974
Cyclobutanones hold a privileged role in enantioselective desymmetrization because their inherent ring strain allows for a variety of unusual reactions to occur. Current strategies include α‐functionalization, rearrangement, and C?C bond activation to directly convert cyclobutanones into a wide range of enantiomerically enriched compounds, including many biologically significant scaffolds. This Minireview provides an overview of state‐of‐the‐art methods that generate complexity from prochiral cyclobutanones in a single operation. 相似文献