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Ramon Arora Jos F. Rodríguez Andrew Whyte Mark Lautens 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202112288
A palladium-catalyzed strategy is presented to synthesize unsymmetrically linked heterocycles within stereoselective tetrasubstituted olefins. This reaction is proposed to occur via a vinyl-PdII intermediate capable of initiating the cyclization of various alkyne-tethered nucleophiles. Products are formed in up to 96 % yield and excellent stereoselectivities are obtained using low catalyst loadings. This transformation was scalable up to 1 mmol and mechanistic studies suggest a syn-carbopalladation of the carbamoyl chloride followed by PdII-catalyzed cyclization of alkyne-tethered nucleophiles. 相似文献
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Andrew J. Warner James R. Lawson Valerio Fasano Dr. Michael J. Ingleson 《Angewandte Chemie (International ed. in English)》2015,54(38):11245-11249
BCl3 is an inexpensive electrophile which induces the borylative cyclization of a wide range of substituted alkynes to regioselectively form polycycles containing synthetically versatile C(sp2)? boronate esters. It proceeds rapidly, with good yields and is compatible with a range of functional groups and substitution patterns. Intermolecular 1,2‐carboboration of alkynes is also achieved using BCl3 to generate trisubstituted vinyl boronate esters. 相似文献
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Dr. Clément F. Heinrich Indira Fabre Dr. Laurence Miesch 《Angewandte Chemie (International ed. in English)》2016,55(17):5170-5174
Cyclization of silylenolether‐ynesulfonamides proceeds at ambient temperature under mild reaction conditions under silver catalysis. Bridged compounds were obtained exclusively through 7‐exo‐dig reactions. The protocol is applicable to a wide range of substrates, thus leading to azabicyclic frameworks. 相似文献
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Rhodium‐Catalyzed Cyclization of O,ω‐Unsaturated Alkoxyamines: Formation of Oxygen‐Containing Heterocycles 下载免费PDF全文
Julien Escudero Prof. Véronique Bellosta Prof. Janine Cossy 《Angewandte Chemie (International ed. in English)》2018,57(2):574-578
O,ω‐Unsaturated N‐tosyl alkoxyamines undergo unexpected RhIII‐catalyzed intramolecular cyclization by oxyamination to produce oxygen‐containing heterocycles. Mechanistic studies show that an aziridine intermediate seems to be responsible for the formation of the heterocycles, possibly via a RhV species. 相似文献
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Dr. Xiaoxun Li Hui Li Wangze Song Po‐Sen Tseng Dr. Lingyan Liu Dr. Ilia A. Guzei Prof. Dr. Weiping Tang 《Angewandte Chemie (International ed. in English)》2015,54(44):12905-12908
Rhodium(I) carbenes were generated from propargylic alcohol derivatives as the result of a dehydrative indole annulation. Depending on the choice of the electron‐withdrawing group on the aniline nitrogen nucleophile, either a cyclopropanation product or dimerization product was obtained chemoselectively. Intramolecular hydroamidation occurred for the same type of propargylic alcohol derivatives when other transition‐metal catalysts were employed. 相似文献
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Renxiao Liang Dr. Kai Chen Qiaohui Zhang Jiantao Zhang Prof. Dr. Huanfeng Jiang Prof. Dr. Shifa Zhu 《Angewandte Chemie (International ed. in English)》2016,55(7):2587-2591
A one‐pot tandem process involving hydrolysis, Knoevenagel condensation, Michael addition, and Conia‐ene (HKMC) reactions has been developed for the rapid synthesis of indanone‐fused 2‐methylene tetrahydrofurans from the reaction of enynals and propynols. In this process, two rings and four bonds are generated with 100 % atom‐economy and high step‐efficiency. The resulting tetrahydrofurans were readily oxidized into α‐methylene γ‐lactones, which are one of the most important substructures in natural and bioactive compounds. 相似文献
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Dr. Johannes P. Schmidt Prof. Dr. Bernhard Breit 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23691-23696
A comprehensive study of a diastereoselective Rh-catalyzed cyclization of terminal and internal allenols is reported. The methodology allows the atom economic and highly syn-selective access to synthetically important 2,4-disubstituted and 2,4,6-trisubstituted tetrahydropyrans (THP). Furthermore, its utility and versatility are demonstrated by a great functional-group compatibility and the enantioselective total synthesis of (−)-centrolobine. 相似文献
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Swadhin Chetia Samprity Sarmah Dr. Apurba Dutta Prof. Diganta Sarma 《European journal of organic chemistry》2023,26(26):e202300390
A copper acetate monohydrate catalyzed simple, effective and economic protocol has been developed for the construction of quinazoline derivatives via acceptorless dehydrogenative coupling of easily available 2-aminoaryl methanols and nitriles. The methodology was also highly effective for the synthesis of medicinally important quinolines analogues. The reactions proceeded in presence of KOtBu in toluene at 110 °C for 5 h without the requirement of inert condition, external additives and ligands. 相似文献
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Interrupted Imino‐Nazarov Cyclization of 1‐Aminopentadienyl Cation and Related Cascade Process 下载免费PDF全文
Ronny William Siming Wang Feiqing Ding Elise Nerissa Arviana Prof. Dr. Xue‐Wei Liu 《Angewandte Chemie (International ed. in English)》2014,53(40):10742-10746
Facile 4π conrotatory imino‐Nazarov cyclization of a 1‐aminopentadienyl cation generated from condensation an aldehyde and secondary aniline in the presence of a catalytic amount of a Lewis acid has been developed. Silver(I)‐catalyzed intramolecular arene trapping of the resulting cyclic oxyallyl cation leads to formation of tricyclic indoline‐fused cyclopentanone. The use of lanthanide salts allows transformation after the initial trapping to afford tetrahydroquinoline‐fused cyclopentenone in a concise manner. 相似文献
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Rhodium‐Catalyzed Tandem Cyclization/SiC Activation Reaction for the Synthesis of Siloles 下载免费PDF全文
Dr. Qing‐Wei Zhang Kun An Prof. Dr. Wei He 《Angewandte Chemie (International ed. in English)》2014,53(22):5667-5671
Siloles represent an important emerging class of photoluminescent materials. Reported herein is a new synthetic strategy involving a tandem cyclization/Si? C activation reaction featuring high efficiency, wide substrate scope, and practical utility. This method enabled the first synthesis of benzofuran siloles as well as rapid access to conjugated siloles. During the course of the study we also uncovered an unusual yet general Si? C(sp2) activation in the presence of π acids. 相似文献
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Dr. Ricardo F. Schumacher Alisson R. Rosário Marlon R. Leite Prof. Dr. Gilson Zeni 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13059-13064
Copper(II) halide mediated cyclization of homopropargyl chalcogenides gave three types of chalcogenophene derivatives. Selective product formation was achieved by controlling solvent, temperature, and atmosphere. By using CuBr2 and 1,2‐dichloroethane at room temperature under ambient atmosphere, 4‐bromo dihydroselenophene derivatives were obtained, whereas CuBr2 and 1,2‐dichloroethane at reflux gave selectively 2‐substituted selenophenes. When 1,2‐dichloroethane was replaced by dimethylacetamide, 3‐halo‐selenophenes were obtained exclusively. The versatility of chalcogenophenes was also studied by reaction of 3‐haloselenophenes with terminal alkynes under Sonogashira conditions affording the cross‐coupled products. In addition, the reaction of 3‐haloselenophenes with boronic acids gave the corresponding Suzuki‐type products in good yields. 相似文献
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Yu‐Hui Wang Jun‐Song Tian Peng‐Wei Tan Qiang Cao Xue‐Xin Zhang Zhong‐Yan Cao Feng Zhou Xin Wang Jian Zhou 《Angewandte Chemie (International ed. in English)》2020,59(4):1634-1643
Azacycles such as indoles and tetrahydroquinolines are privileged structures in drug development. Reported here is an unprecedented regiodivergent intramolecular nucleophilic addition reaction of imines as a flexible approach to access N‐functionalized indoles and tetrahydroquinolines, by the control of reaction at the N‐terminus and C‐terminus, respectively. Using ketimines derived from 2‐(2‐nitroethyl)anilines with isatins or α‐ketoesters, the regioselective N‐attack reaction gives N‐functionalized indoles, while the catalytic enantioselective C‐attack reaction affords chiral tetrahydroquinolines featuring an α‐tetrasubstituted stereocenter. Mechanistic studies reveal that hydrogen‐bonding interactions may greatly facilitate such unusual N‐attack reactions of imines. The utility of this protocol is highlighted by the catalytic enantioselective formal synthesis of (?)‐psychotrimine, and the construction of various fused aza‐heterocycles. 相似文献
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Skeletal Rearrangement of O‐Propargylic Formaldoximes by a Gold‐Catalyzed Cyclization/Intermolecular Methylene Transfer Sequence 下载免费PDF全文
Prof. Dr. Itaru Nakamura Shinya Gima Yu Kudo Prof. Dr. Masahiro Terada 《Angewandte Chemie (International ed. in English)》2015,54(24):7154-7157
Skeletal rearrangement of O‐propargylic formaldoximes, in the presence of gold catalysts, afforded 4‐methylene‐2‐isoxazolines in good to excellent yields by an intermolecular methylene transfer. In addition, the cascade reaction with maleimide in the presence of a gold catalyst afforded isoxazole derivatives by cyclization/methylene transfer and a subsequent ene reaction, whereas that using a copper catalyst gave oxazepines through a 2,3‐rearrangement. 相似文献
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Gold‐Catalyzed 1,2‐Acyloxy Migration/Intramolecular [3+2] 1,3‐Dipolar Cycloaddtion Cascade Reaction: An Efficient Strategy for Syntheses of Medium‐Sized‐Ring Ethers and Amines 下载免费PDF全文
Changgui Zhao Dr. Xingang Xie Shuangshuang Duan Huilin Li Dr. Ran Fang Prof. Dr. Xuegong She 《Angewandte Chemie (International ed. in English)》2014,53(40):10789-10793
A highly efficient strategy for the formation of medium‐sized‐ring ethers and amines based on a gold‐catalyzed cascade reaction, involving enynyl ester isomerization and intramolecular [3+2] cyclization, has been developed. Various multisubstituted medium‐sized‐ring unsaturated ethers and amines were obtained through this transformation. This method represents one of the relatively few transition metal catalyzed intramolecular cycloaddition reactions for medium‐sized ring synthesis. 相似文献
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Wang C Wang C Wang Q Wang Z Sun H Guo X Xi Z 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(22):6484-6494
Stereodefined multisubstituted 1-cyano- and 1,4-dicyano-1,3-butadiene derivatives were obtained in excellent yields of the isolated product from their corresponding monohalo- and dihalobutadienes and CuCN. This reaction proceeded with high stereoselectivity and retention of the stereochemistry of the starting halobutadienes. A study of the utility of the thus-obtained 1-cyano- and 1,4-dicyano-1,3-butadiene derivatives was demonstrated by their reactions with organolithium reagents. 2H-Pyrrole or iminocyclopentadiene derivatives were formed in high yields from 1-cyano-4-halo-1,3-butadienes and organolithium reagents. When 1,4-dicyano-1,3-butadienes were treated with organolithium reagents followed by trapping with electrophiles, a tandem process took place to afford 2H-pyrrolyl nitriles in excellent yields. Reduction of 1,4-dicyano-1,3-butadiene derivatives with LiAlH4 showed novel reaction patterns relative to normal nitriles. 相似文献
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Hai Huang Junzhen Fan Dr. Guangke He Zhimin Yang Xiaodong Jin Qi Liu Prof. Dr. Hongjun Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2532-2538
A novel method for metal‐free oxothiolation of ynamides to construct oxazolidine‐2,4‐diones bearing sulfur‐substituted quaternary carbon atoms has been developed. It represents a rare C?O bond cleavage of ynamides, as well as a facile and tandem approach for the formation of C?O, C?S, and C?Cl bonds. This redox‐neutral protocol can be applied to the synthesis of multisubstituted oxazolidine‐2,4‐diones with good chemoselectivity and good yields of isolated products under mild conditions. 相似文献
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Transition from π Radicals to σ Radicals: Substituent‐Tuned Cyclization of Hydrazonyl Radicals 下载免费PDF全文
Xiu‐Long Yang Prof. Dr. Wei Yu Prof. Dr. Bing Han 《Angewandte Chemie (International ed. in English)》2014,53(12):3158-3162
Hydrazonyl radicals are known for their π‐electronic structures; however, their σ‐electronic structures have not been reported as yet. Herein, we show that readily accessible β,γ‐ and γ,δ‐unsaturated N‐trichloroacetyl and N‐trifluoroacetyl hydrazones can be conveniently converted into hydrazonyl σ radicals, which subsequently undergo 5‐exo‐trig radical cyclization at the N1 or N2 atom to form pyrazolines and azomethine imines, respectively. 相似文献