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1.
[reaction: see text]. A novel, microwave-enhanced, highly efficient protocol for the synthesis of hitherto unknown (-)-steganacin and (-)-steganone 7-aza analogues containing a 1,2,3-triazole ring has been presented. Microwave irradiation was found to be highly beneficial in promoting the Suzuki reaction and the 1,3-dipolar cycloaddition reaction to generate the highly strained medium-sized ring system of the title molecules. 相似文献
2.
[reaction: see text] Starting from (-)-quinic acid an efficient synthesis of highly functionalized cis-alpha,beta-unsaturated ketone 3, an advanced precursor of branimycin, has been accomplished via two key step reactions: a ring closing metathesis reaction to prepare the cis-decalin system, and a highly stereoselective epoxidation reaction. 相似文献
3.
Ali Ramazani Abbas Azizian Maryam Bandpey Nader Noshiranzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2731-2734
Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 2,2,2-trichloroethanol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding chlorine-containing stabilized phosphorus ylides. An intermolecular Wittig reaction of the chlorine-containing stabilized phosphorus ylides with ninhydrin leads to the corresponding highly electron-poor chlorine-containing alkenes. 相似文献
4.
A highly diastereoselective cross aldol reaction is developed using divalent tin enolates formed from stannous trifluoromethanesulfonate and carbonyl compounds. The reaction is extended to a highly enantioselective cross aldol reaction employing chiral diamines derived from (S)-proline as ligands. 相似文献
5.
The Mannich reaction is one of the most widely utilized chemical transformations for the construction of nitrogen-containing compounds. With the increasing occurrence of nitrogen in drugs and natural products, highly asymmetric variants of the Mannich reaction are desirable. In this communication, we report the application of our dinuclear zinc catalyst to a highly asymmetric Mannich-type reaction to generate syn 1,2-amino alcohols. 相似文献
6.
Powell SA Tenenbaum JM Woerpel KA 《Journal of the American Chemical Society》2002,124(43):12648-12649
We have developed a route for the stereoselective synthesis of 1-oxa-2,2-(dimesityl)silacyclopentane acetals, intermediates in the synthesis of highly functionalized 1,3-diols. This route involves a diastereoselective conjugate addition reaction of a hydrosilyl anion, a subsequent diastereoselective enolate alkylation, and a fluoride-catalyzed intramolecular hydrosilylation reaction to afford the oxasilacyclopentane acetal. A highly selective nucleophilic substitution reaction, followed by oxidation of the C-Si bond, leads to the desired polyol. 相似文献
7.
Jiuzhou Guo Bo Li Weihao Ma Dr. Mallesham Pitchakuntla Prof. Yanxing Jia 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15307-15310
A practically useful method for the formation of the highly oxygenated bicyclo[3.2.1]octane ring system through Mn(OAc)3-mediated radical cyclization of alkynyl ketones was developed, which opens up a new avenue for the total synthesis of a number of highly oxidized diterpenoids. Application of this method enabled the first total synthesis of (−)-glaucocalyxin A. Other salient features of the synthesis include a highly enantioselective conjugate addition/acylation cascade reaction, a Yamamoto aldol reaction, and an intramolecular Diels–Alder reaction to assemble the A/B ring system. 相似文献
8.
A highly stereo- and chemoselective glycosylation of H-phosphonate derivatives with glycosyl iodides was discovered as a reverse reaction of the formation of a glycosyl iodide from a glycosyl phosphite and I- under mild acidic conditions. Further study on the unique reaction showed that the reaction provided various alpha-glycosyl phosphites and phosphoramidites in a highly stereoselective manner with complete O-selectivity. 相似文献
9.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7548-7551
A highly efficient synthesis of the enantioenriched tetrahydro‐β‐carbolines was developed by using a chiral phosphoric acid catalyzed Pictet–Spengler reaction of indolyl dihydropyridines. The reaction proceeds under mild reaction conditions to afford the desired chiral tetrahydro‐β‐carbolines in good to excellent yields (up to 96 %) and high enantioselectivities (up to 99 % ee ). With this method, a formal synthesis of tangutorine and a total synthesis of deplancheine were achieved in a highly efficient manner. 相似文献
10.
Dr. Shou-Guo Wang Zi-Lei Xia Ren-Qi Xu Xi-Jia Liu Dr. Chao Zheng Prof. Dr. Shu-Li You 《Angewandte Chemie (International ed. in English)》2017,56(26):7440-7443
A highly efficient synthesis of the enantioenriched tetrahydro-β-carbolines was developed by using a chiral phosphoric acid catalyzed Pictet–Spengler reaction of indolyl dihydropyridines. The reaction proceeds under mild reaction conditions to afford the desired chiral tetrahydro-β-carbolines in good to excellent yields (up to 96 %) and high enantioselectivities (up to 99 % ee). With this method, a formal synthesis of tangutorine and a total synthesis of deplancheine were achieved in a highly efficient manner. 相似文献
11.
Dr. S. Maryamdokht Taimoory Dr. Vincenzo Alessandro Cataldo Dr. Andreas Schäfer Prof. John F. Trant Dr. Ryan Guterman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3440-3448
Alkylating reagents based on thioimidazolium ionic liquids were synthesized and the influence of the anion on the alkylation reaction mechanism explored in detail using both experimental and computational methods. Thioimidazolium cations transfer alkyl substituents to nucleophiles, however the reaction rate was highly dependent on anion identity, demonstrating that the anion is not innocent in the mechanism. Detailed analysis of the computationally-derived potential energy surfaces associated with possible mechanisms indicated that this dependence arises from a combination of anion induced electronic, steric and coordinating effects, with highly nucleophilic anions catalyzing a 2-step process while highly non-nucleophilic, delocalized anions favor a 1-step reaction. This work also confirms the presence of ion-pairs and aggregates in solution thus supporting anion-induced control over the reaction rate and mechanism. These findings provide new insight into an old reaction allowing for better design of cationic alkylators in synthesis, gene expression, polymer science, and protein chemistry applications. 相似文献
12.
Jiuzhou Guo Bo Li Weihao Ma Mallesham Pitchakuntla Yanxing Jia 《Angewandte Chemie (International ed. in English)》2020,59(35):15195-15198
A practically useful method for the formation of the highly oxygenated bicyclo[3.2.1]octane ring system through Mn(OAc)3‐mediated radical cyclization of alkynyl ketones was developed, which opens up a new avenue for the total synthesis of a number of highly oxidized diterpenoids. Application of this method enabled the first total synthesis of (?)‐glaucocalyxin A. Other salient features of the synthesis include a highly enantioselective conjugate addition/acylation cascade reaction, a Yamamoto aldol reaction, and an intramolecular Diels–Alder reaction to assemble the A/B ring system. 相似文献
13.
The highly enantioselective cinchona alkaloid-catalyzed Mannich reaction of dicarbonyl compounds with alpha-amido sulfones as acyl imine precursors is described. The reaction requires 10 mol % of the cinchona alkaloid catalyst, which serves as a general base to generate acyl imines in situ, and aqueous Na2CO3 to maintain the concentration of free alkaloid catalyst. The reaction products are obtained in good yields and high enantioselectivities, and in diastereoselectivities that range from 1:1 to >95:5. The cinchonine-catalyzed reactions provide practical access to highly functionalized building blocks which have been employed in the synthesis of chiral dihydropyrimidones, a class of compounds rich in diverse biological activity. Dihydropyrimidone modifications include a highly diastereoselective hydrogenation of the enamide moiety, using an H-Cube flow hydrogenator and a Rh(II)-mediated 1,3-dipolar cycloaddition to afford highly functionalized complex heterocycles. 相似文献
14.
Rahim Hekmatshoar Sanaz Souri Mahshid Rahimifard Farnoosh Faridbod 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2827-2833
Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate(DMAD) by substituted phenols lead to vinyl triphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with a phenolate conjugate base to produce 4-carboxymethyl coumarins in fairly highly yields. 相似文献
15.
16.
Anna Esposito Concetta di Giovanni Dr. Maria De Fenza Prof. Giovanni Talarico Dr. Marco Chino Prof. Giovanni Palumbo Dr. Annalisa Guaragna Dr. Daniele D'Alonzo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2597-2601
A highly regio- and stereoselective route to d - and l -cyclohexenyl nucleosides has been devised, using the Tsuji–Trost reaction as the key step. Contrarily to the widely accepted mechanism (involving a net retention of configuration), the reaction proceeded in a highly stereoconvergent manner, providing cis nucleosides regardless of the relative configuration of the starting materials. DFT calculations confirmed the experimental data while suggesting the origin of the stereochemical reaction outcome. 相似文献
17.
Baik MH Mazumder S Ricci P Sawyer JR Song YG Wang H Evans PA 《Journal of the American Chemical Society》2011,133(20):7621-7623
The computational analysis of the rhodium-catalyzed Pauson-Khand reaction indicates that the key transition state is highly charge-polarized, wherein different diastereoisomers have distinctively different charge polarization patterns. Experimental studies demonstrate that chloro-enynes provide the optimal σ-electron-withdrawing group to promote polarization and thereby reduce the activation barrier to provide a highly diastereoselective reaction at room temperature. 相似文献
18.
The development of highly enantioselective and general catalytic nitroaldol (Henry) reactions with ketones is a challenging yet desirable task in organic synthesis. In this communication, we report an asymmetric nitroaldol reaction with alpha-ketoesters catalyzed by a new C6'-OH cinchona alkaloid catalyst. This is the first highly efficient organocatalytic asymmetric Henry reaction with ketones. This reaction is operationally simple and affords high enantioselectivity as well as good to excellent yield for a broad range of alpha-ketoesters. 相似文献
19.
A highly efficient carbon-carbon triple bond cleavage reaction of (Z)-enynols was developed, which offered a new route to highly substituted butenolides. The methodology is realized by a tandem reaction using a single gold(I) catalyst, which could catalyze different reactions of cyclization/oxidative cleavage in the same vessel. 相似文献
20.
Shan Yang Tianze Zheng Dr. Longhui Duan Dr. Xiaoping Xue Prof. Zhenhua Gu 《Angewandte Chemie (International ed. in English)》2023,62(21):e202302749
A copper-catalyzed atroposelective ring-opening reaction of cyclic diaryliodoniums, sodium cyanate (NaOCN) and phenols is reported. The reaction chemoselectively affords axially chiral carbamates by sequential coupling of cyclic diaryliodonium and NaOCN, followed by phenol. Mechanistic investigations revealed that phenol is not only a reagent to trap highly active intermediate isocyanates, but it also activates the copper catalyst as a standby ligand. The carbamates were readily transformed into highly functionalized urea derivatives within a simple nucleophilic substitution reaction. 相似文献