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1.
Double‐Addition Reaction of Aryl Methyl Sulfones with N‐tert‐Butylsulfinyl Imines: Diastereoselective and Concise Synthesis of 2‐Sulfonylated 1,3‐Diamines 下载免费PDF全文
Prof. Dr. Ya Li Desheng Li Tao Zheng Dr. Hongsen Li Dr. Xinfeng Ren 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):14986-14990
We report a double‐addition reaction of methyl phenyl sulfone and methyl 2‐pyridyl sulfone with N‐tert‐butylsulfinyl imines. This method provides concise access to 2‐sulfonylated 1,3‐anti diamines with good to excellent diastereoselectivities. This protocol has the benefit of using readily accessible starting materials and is operationally simple. 相似文献
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Miguel Espinosa Prof. Dr. Gonzalo Blay Prof. Dr. Luz Cardona Prof. Dr. José R. Pedro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14861-14866
The asymmetric conjugate addition of malonate esters to α,β‐unsaturated N‐sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 Å MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ‐aminoesters and piperidones. 相似文献
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Highly Diastereo‐ and Enantioselective Michael Addition of Nitroalkanes to 2‐Enoyl‐Pyridine N‐Oxides Catalyzed by Scandium(III)/Copper(II) Complexes 下载免费PDF全文
Lijun Li Sheng Zhang Yanbin Hu Yanan Li Chong Li Prof. Zhenggen Zha Prof. Dr. Zhiyong Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):12885-12888
A C2‐symmetric Schiff‐base ligand, derived from tridentate‐Schiff‐base, was developed and successfully applied to the asymmetric Michael addition of nitroalkanes to 2‐enoyl‐pyridine N‐oxides. With this newly catalytic system, an unprecedented diastereoselectivity was obtained in the asymmetric Michael addition of nitroalkanes to 2‐enoyl‐pyridine N‐oxides. In addition, a switch in enantioselectivity was achieved by using this newly catalytic system and our previous catalyst. After a facile reduction, the optically active adduct was converted to a biologically active dihydro‐2H‐pyrrol 4 a . Furthermore, a connection of two tridentate‐Schiff‐base subunits proved to be an effective strategy in ligand design. 相似文献
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《Angewandte Chemie (International ed. in English)》2017,56(20):5612-5615
In the presence of a catalytic amount of chiral phosphoric acid, nucleophilic addition of N ‐monosubstituted hydrazones to N ‐Boc imines affords differentially protected vicinal diamines in the form of β‐amino N ,N ′‐dialkyldiazenes in excellent yields with high chemo‐, diastereo‐, and enantioselectivity. This catalytic asymmetric aza‐Mannich reaction represents the first example in which N ‐alkyl hydrazones serve as α‐azo carbanion equivalents to provide vicinal diamines with control of the two contiguous stereocenters. The adducts are readily converted into the monoprotected or free diamines and derivatives thereof. 相似文献
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Regiodivergent Synthesis of 1,3‐ and 1,4‐Enynes through Kinetically Favored Hydropalladation and Ligand‐Enforced Carbopalladation 下载免费PDF全文
Dr. Tapas R. Pradhan Hong Won Kim Prof. Dr. Jin Kyoon Park 《Angewandte Chemie (International ed. in English)》2018,57(31):9930-9935
Pd‐catalyzed hydroalkynylations were developed that involve ligand‐enabled regiodivergent addition of an alkyne to an allenamide, giving branched and linear products stereoselectively and facilitated by the neighboring amide group. Regioselectivity was achieved with the use of (o‐OMePh)3P and BrettPhos, which allowed the functionalization of various alkynes, including steroids, carbohydrates, alkaloids, chiral ligands, and vitamins. Based on the experimental results, it was proposed that hydro‐ and carbopalladation processes operated during the formations of the branched and linear products, respectively. 相似文献
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Dr. Damien Bonne Prof. Dr. Thierry Constantieux Dr. Yoann Coquerel Prof. Dr. Jean Rodriguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(7):2218-2231
Although long known, 1,2‐ and 1,3‐dicarbonyl compounds have recently come more and more to prevalence as ideal substrates for the invention of new stereoselective multiple bond‐forming transformations (MBFTs). Herein, a critical appraisal is presented of some of the most spectacular of these MBFTs, which allow the formation from three up to six bonds in highly step‐ and atom‐economical processes. 相似文献
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Chiral Calcium–BINOL Phosphate Catalyzed Diastereo‐ and Enantioselective Synthesis of syn‐1,2‐Disubstituted 1,2‐Diamines: Scope and Mechanistic Studies 下载免费PDF全文
Dr. Claudia Lalli Audrey Dumoulin Clément Lebée Dr. Fleur Drouet Vincent Guérineau Dr. David Touboul Prof. Dr. Vincent Gandon Prof. Dr. Jieping Zhu Dr. Géraldine Masson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(4):1704-1712
A highly enantioselective, chiral, Lewis acid calcium–bis(phosphate) complex, Ca[ 3 a ]n, which catalyzes the electrophilic amination of enamides with azodicarboxylate derivatives 2 to provide versatile chiral 1,2‐hydrazinoimines 4 is disclosed. The reaction gives an easy entry to optically active syn‐1,2‐disubstituted 1,2‐diamines 6 in high yields with excellent enantioselectivities, after a one‐pot reduction of the intermediate 1,2‐hydrazinoimines 4 . The geometry and nature of the N‐substituent of the enamide affect dramatically both the reactivity and the enantioselectivity. Although the calcium–bis(phosphate) complex was a uniquely effective catalyst, the exact nature of the active catalytic species remains unclear. NMR spectroscopy and MS analysis of the various calcium complexes Ca[ 3 ]n reveals that the catalysts exist in various oligomer forms. The present mechanistic study, which includes nonlinear effects and kinetic measurements, constitutes a first step in understanding these calcium–bis(phosphate) complex catalysts. DFT calculations were carried out to explore the mechanism and the origin of the enantioselectivity with the Ca[ 3 ]n catalysts. 相似文献
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Mehdi Adib Ehsan Sheikhi Morteza Karimzadeh Hamid Reza Bijanzadeh Massoud Amanlou 《Helvetica chimica acta》2012,95(5):788-794
A simple synthesis of N2‐alkyl‐N3‐[2‐(1,3,4‐oxadiazol‐2‐yl)aryl]benzofuran‐2,3‐diamines 5 via a one‐pot four‐component reaction is described (Scheme 1). A mixture of N‐(isocyanoimino)triphenylphosphorane ( 1 ), a 2‐aminobenzoic acid 2 , a 2‐hydroxybenzaldehyde 3 , and an isocyanide 4 in absolute EtOH at room temperature undergoes a smooth reaction to afford 5 in excellent yields (Table). 相似文献
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Divergent Synthesis of CF3‐Substituted Allenyl Nitriles by Ligand‐Controlled Radical 1,2‐ and 1,4‐Addition to 1,3‐Enynes 下载免费PDF全文
Fei Wang Dinghai Wang Yu Zhou Ling Liang Ronghua Lu Dr. Pinhong Chen Prof. Dr. Zhenyang Lin Prof. Dr. Guosheng Liu 《Angewandte Chemie (International ed. in English)》2018,57(24):7140-7145
A ligand‐controlled system that enables regioselective trifluoromethylcyanation of 1,3‐enynes has been identified, which provides access to a variety of CF3‐containing tri‐ and tetrasubstituted allenyl nitriles. We disclose that the involved propargylic radicals can be selectively trapped by (Box)CuII cyanide, while the tautomerized allenyl radicals are trapped by (phen)CuII cyanide (Box= bisoxazoline, phen=phenanthroline). In addition, the reaction features broad substrate scope and excellent functional group compatibility. Moreover, this protocol represents a novel regioselectivity‐tunable functionalization of 1,3‐enynes via radicals, which we believe will have great implications for the development of catalytic systems for selectivity control in radical and organometallic chemistry. 相似文献
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β,γ‐Unsaturated ketones are an important class of organic molecules. Herein, copper catalysis has been developed for the synthesis of β‐γ‐unsaturated ketones through 1,2‐addition of α‐carbonyl iodides to alkynes. The reactions exhibit wide substrate scope and high functional group tolerance. The reaction products are versatile synthetic intermediates to complex small molecules. The method was applied for the formal synthesis of (±)‐trichostatin A, a histone deacetylase inhibitor. 相似文献
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Catalyst‐Directed Diastereo‐ and Site‐Selectivity in Successive Nucleophilic and Electrophilic Allylations of Chiral 1,3‐Diols: Protecting‐Group‐Free Synthesis of Substituted Pyrans 下载免费PDF全文
Dr. Inji Shin Gang Wang Prof. Michael J. Krische 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13382-13389
The iridium‐catalyzed, protecting group‐free synthesis of 4‐hydroxy‐2,6‐cis‐ or trans‐pyrans through successive nucleophilic and electrophilic allylations of chiral 1,3‐diols occurs with complete levels of catalyst‐directed diastereoselectivity in the absence of protecting groups, premetallated reagents, or discrete alcohol‐to‐aldehyde redox reactions. 相似文献
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Organocatalytic Enantio‐ and Diastereoselective Conjugate Addition to Nitroolefins: When β‐Ketoamides Surpass β‐Ketoesters 下载免费PDF全文
Haiying Du Prof. Dr. Jean Rodriguez Dr. Xavier Bugaut Prof. Dr. Thierry Constantieux 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8458-8466
Our findings on the bifunctional squaramide‐catalyzed enantioselective conjugate addition of β‐ketoamides to nitroolefins are disclosed. It appears that simple acyclic methylene β‐ketoamides, unlike the extensively studied β‐ketoesters, afford the products in excellent diastereoselectivities, and maintain high yields and enantioselectivities. Moreover, competition and kinetic studies were conducted to rationalize the observed reactivity and selectivity. The high level of diastereocontrol, along with the amenability of the amide group to postfunctionalization, dramatically increase the synthetic usefulness of the transformation. 相似文献
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Regio‐ and Chemoselective N‐1 Acylation of Indoles: Pd‐Catalyzed Domino Cyclization to Afford 1,2‐Fused Tricyclic Indole Scaffolds 下载免费PDF全文
Yongxian Liu Yuanqiong Huang Hongjian Song Yuxiu Liu Prof. Qingmin Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5337-5340
A concise method for the synthesis of 1,2‐fused tricyclic indole scaffolds by domino cyclization involving a Pd‐catalyzed Sonogashira coupling, indole cyclization, regio‐ and chemoselective N‐1 acylation, and 1,4‐Michael addition is reported. This method provides straightforward access to tetrahydro[1,4]diazepino[1,2‐a]indole and hexahydro[1,5]diazocino[1,2‐a]indole scaffolds. 相似文献
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A Metal‐Free Three‐Component Reaction for the Regioselective Synthesis of 1,4,5‐Trisubstituted 1,2,3‐Triazoles 下载免费PDF全文
Dr. Joice Thomas Dr. Jubi John Nikita Parekh Prof. Dr. Wim Dehaen 《Angewandte Chemie (International ed. in English)》2014,53(38):10155-10159
A metal‐free three‐component reaction to synthesize 1,4,5‐trisubstituted 1,2,3‐triazoles from readily available building blocks, such as aldehydes, nitroalkanes, and organic azides, is described. The process is enabled by an organocatalyzed Knoevenagel condensation of the formyl group with the nitro compound, which is followed by the 1,3‐dipolar cycloaddition of the azide to the activated alkene. The reaction features an excellent substrate scope, and the products are obtained with high yield and regioselectivity. This method can be utilized for the synthesis of fused triazole heterocycles and materials with several triazole moieties. 相似文献
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Highly Chemo‐, Enantio‐, and Regioselective Synthesis of α,α‐Disubstituted Furanones by Cu‐Catalyzed Conjugate Addition 下载免费PDF全文
Prof. Dr. Kohei Endo Prof. Dr. Takanori Shibata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):8893-8897
A highly chemo‐, enantio‐, and regioselective synthesis of furanones bearing an α,α‐disubstituted quaternary stereogenic center is reported. The Cu‐catalyzed enantioselective conjugate addition of organoaluminum reagents to unsaturated ketoesters at room temperature and subsequent lactonization took place. Synthetic transformations of furanones represent facile approaches to various cyclic or acyclic compounds bearing a quaternary stereogenic center. 相似文献