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Iridium‐Catalyzed Enantioselective Allylic Alkylation with Functionalized Organozinc Bromides 下载免费PDF全文
James Y. Hamilton Dr. David Sarlah Prof. Dr. Erick M. Carreira 《Angewandte Chemie (International ed. in English)》2015,54(26):7644-7647
Iridium‐catalyzed enantioselective allylic alkylation of branched racemic carbonates with functionalized alkylzinc bromide reagents is described. Enabled by a chiral Ir/(P,olefin) complex, the method described allows allylic substitution with various primary and secondary alkyl nucleophiles with excellent regio‐ and enantioselectivities. The developed reaction was showcased in a concise, asymmetric synthesis of (?)‐preclamol. 相似文献
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A synergistic catalysis combination of chiral‐at‐metal rhodium complex and amine catalyst was developed for enantioselective alkylation of aldehydes with α,β‐unsaturated 2‐acyl imidazoles. The corresponding adducts were obtained in good yields with excellent enantioselectivities (up to 99% ee). 相似文献
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Enantioselective Synthesis of Vicinal All‐Carbon Quaternary Centers via Iridium‐Catalyzed Allylic Alkylation 下载免费PDF全文
Dr. J. Caleb Hethcox Samantha E. Shockley Prof. Dr. Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2018,57(28):8664-8667
The development of the first enantioselective transition‐metal‐catalyzed allylic alkylation providing access to acyclic products bearing vicinal all‐carbon quaternary centers is disclosed. The iridium‐catalyzed allylic alkylation reaction proceeds with excellent yields and selectivities for a range of malononitrile‐derived nucleophiles and trisubstituted allylic electrophiles. The utility of these sterically congested products is explored through a series of diverse chemo‐ and diastereoselective product transformations to afford a number of highly valuable, densely functionalized building blocks, including those containing vicinal all‐carbon quaternary stereocenters. 相似文献
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Carina I. Jette Z. Jaron Tong Ryan G. Hadt Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2020,59(5):2033-2038
Herein, we report a Cu‐catalyzed enantioselective allylic alkylation using a γ‐butyrolactone‐derived silyl ketene acetal. Critical to the development of this work was the identification of a novel mono‐picolinamide ligand with the appropriate steric and electronic properties to afford the desired products in high yield (up to 96 %) and high ee (up to 95 %). Aryl, aliphatic, and unsubstituted allylic chlorides bearing a broad range of functionality are well‐tolerated. Spectroscopic studies reveal that a CuI species is likely the active catalyst, and DFT calculations suggest ligand sterics play an important role in determining Cu coordination and thus catalyst geometry. 相似文献
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The efficiency and selectivity of Cu‐catalyzed allylic acetoxylation of alkene in different solvent systems is improved by the presence of different metallic salts in the reaction medium. The methodology is particularly well employed for the direct allylic acetoxylation of Δ5‐steroids at 7‐position, for which the resulting acetoxylated product obtained was exclusively α‐isomer. Excellent yield was achieved (up to 90%) under optimized conditions, while significantly reducing the costs and environmental hazards and increasing the yield as compared to the other previously reported methods. 相似文献
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Dr. J. Caleb Hethcox Samantha E. Shockley Prof. Dr. Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2016,55(52):16092-16095
The development of the first enantio‐, diastereo‐, and regioselective iridium‐catalyzed allylic alkylation reaction of prochiral enolates to form an all‐carbon quaternary stereogenic center with an aliphatic‐substituted allylic electrophile is disclosed. The reaction proceeds with good to excellent selectivity with a range of substituted tetralone‐derived nucleophiles furnishing products bearing a newly formed vicinal tertiary and all‐carbon quaternary stereodyad. The utility of this protocol is further demonstrated via a number of synthetically diverse product transformations. 相似文献
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Iridium‐Catalyzed Diastereoselective and Enantioselective Allylic Substitutions with Acyclic α‐Alkoxy Ketones 下载免费PDF全文
Xingyu Jiang Wenyong Chen Prof. John F. Hartwig 《Angewandte Chemie (International ed. in English)》2016,55(19):5819-5823
The asymmetric alkylation of acyclic ketones is a longstanding challenge in organic synthesis. Reported herein are diastereoselective and enantioselective allylic substitutions with acyclic α‐alkoxy ketones catalyzed by a metallacyclic iridium complex to form products with contiguous stereogenic centers derived from the nucleophile and electrophile. These reactions occur between allyl methyl carbonates and unstabilized copper(I) enolates generated in situ from acyclic α‐alkoxy ketones. The resulting products can be readily converted into enantioenriched tertiary alcohols and tetrahydrofuran derivatives without erosion of enantiomeric purity. 相似文献
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Asymmetric Allylic Alkylation of β‐Ketoesters with Allylic Alcohols by a Nickel/Diphosphine Catalyst 下载免费PDF全文
Dr. Yusuke Kita Dr. Rahul D. Kavthe Hiroaki Oda Prof. Dr. Kazushi Mashima 《Angewandte Chemie (International ed. in English)》2016,55(3):1098-1101
Asymmetric allylic alkylation of β‐ketoesters with allylic alcohols catalyzed by [Ni(cod)2]/(S)‐H8‐BINAP was found to be a superior synthetic protocol for constructing quaternary chiral centers at the α‐position of β‐ketoesters. The reaction proceeded in high yield and with high enantioselectivity using various β‐ketoesters and allylic alcohols, without any additional activators. The versatility of this methodology for accessing useful and enantioenriched products was demonstrated. 相似文献
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Yaping Wang Walter Weissensteiner Kurt Mereiter Felix Spindler 《Helvetica chimica acta》2006,89(8):1772-1782
The two diphosphine ligands (Rp,Rp)‐ and (Sp,Sp)‐bis[2‐(diphenylphospino)ferrocenyl]methane, (Rp,Rp)‐ and (Sp,Sp)‐ 1 , resp., were prepared in six steps from (S)‐ and (R)‐ferrocenyl tolyl sulfoxide, respectively (Scheme). In the solid state, both the diborane complex (Rp,Rp)‐ 1 ? (BH3)2 and the palladium dichloride complex [PdCl2((Rp,Rp)‐ 1 )] were found to adopt C2‐pseudosymmetric structures according to X‐ray analyses (Figs. 2 and 3). In the Rh‐ and Ru‐catalyzed hydrogenation of selected alkenes and ketones in the presence of the new ligands, enantioselectivities of up to 55% ee were obtained. 相似文献
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Chiral Primary Amine/Palladium Dual Catalysis for Asymmetric Allylic Alkylation of β‐Ketocarbonyl Compounds with Allylic Alcohols 下载免费PDF全文
Han Zhou Dr. Long Zhang Changming Xu Prof. Dr. Sanzhong Luo 《Angewandte Chemie (International ed. in English)》2015,54(43):12645-12648
An efficient dual catalytic system composed of a chiral primary amine and a palladium complex was developed to promote the direct asymmetric allylic alkylation (AAA) of β‐ketocarbonyl compounds. In particular, the synergistic dual catalytic system enabled the AAA reaction of challenging acyclic aliphatic ketones, such as β‐ketocarbonyl compounds and 1,3‐diketones. 相似文献