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Enantioselective Palladium‐Catalyzed [3+2] Cycloaddition of Trimethylenemethane and Fluorinated Ketones
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Prof. Dr. Barry M. Trost Dr. Guillaume Mata 《Angewandte Chemie (International ed. in English)》2018,57(38):12333-12337
A nitrile‐substituted trimethylenemethane (TMM) donor undergoes palladium‐catalyzed [3+2] cycloadditions with fluorinated ketones to generate tetrasubstituted trifluoromethylated centers in high enantioselectivity under mild conditions. The generation of the palladium–TMM complex was achieved by a self‐deprotonation strategy, which shows remarkable improvements in regiocontrol, efficiency, and atom economy of asymmetric [3+2] cycloadditions. Moreover, the versatility of the nitrile group provides direct access to a variety of synthetically useful intermediates, including amides, aldehydes, and esters. The developed reaction conditions allow for the synthesis of a wide variety of aromatic, heteroaromatic, and aliphatic fluorinated dihydrofurans in excellent regio‐ and enantioselectivities. 相似文献
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《Mendeleev Communications》2020,30(6):785-787
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Michail N. Elinson Anatoly N. Vereshchagin Yuliya E. Ryzhkova Mikhail P. Egorov 《Mendeleev Communications》2021,31(3):347-349
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Barluenga J Nandy SK Laxmi YR Suárez JR Merino I Flórez J García-Granda S Montejo-Bernardo J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(23):5725-5736
The sequential low-temperature addition reaction of an organolithium compound and methyl triflate to (menthyloxy)(3-furyl)carbene complexes of chromium and tungsten proceeded with excellent regioselectivity (1,4-addition) and diastereoselectivity (2,3-trans disposition of the nucleophile and electrophile groups) to afford new 2,3-disubstituted (2,3-dihydro-3-furyl)carbene complexes. In addition, a high degree of diastereofacial selectivity was achieved by employing alkenyllithium compounds. After detachment of both the metal fragment and the chiral auxiliary group, trisubstituted 2,3-dihydrofuran derivatives containing a quaternary stereogenic center at the C3 position were obtained. The characterization, including X-ray crystallography, of a novel type of stable four-membered chelate (eta(2)-alkene)tetracarbonylcarbene complex of chromium is also reported. 相似文献
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Radical cyclization reactions of both aliphatic 1,3‐diones 1a and 1b and of cyclic 1,3‐diones 1c – 1e with 2‐thienyl‐ and 3‐thienyl‐substituted alkenes 2a – 2d in the presence of manganese(III) acetate were investigated. Thienyl‐substituted dihydrofurans 3 were obtained with moderate to high yields (Table 1–3). Also, the favorable effect of the thienyl substituent on the intermediate carbocation stability was evaluated by comparison with a phenyl substituent. 相似文献
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Enantioselective Synthesis of Highly Functionalized Dihydrofurans through Copper‐Catalyzed Asymmetric Formal [3+2] Cycloaddition of β‐Ketoesters with Propargylic Esters
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Fu‐Lin Zhu Ya‐Hui Wang De‐Yang Zhang Prof. Dr. Jie Xu Prof. Dr. Xiang‐Ping Hu 《Angewandte Chemie (International ed. in English)》2014,53(38):10223-10227
An enantioselective synthesis of highly functionalized dihydrofurans through a copper‐catalyzed asymmetric [3+2] cycloaddition of β‐ketoesters with propargylic esters has been developed. With a combination of Cu(OTf)2 and a chiral tridentate P,N,N ligand as the catalyst, a variety of 2,3‐dihydrofurans bearing an exocyclic double bond at the 2 position were obtained in good chemical yields and with good to high enantioselectivities. The exocyclic double bond can be hydrogenated in a highly diastereoselective fashion to give unusual cis‐2,3‐dihydrofuran derivatives, thus further enhancing the scope of this transformation. 相似文献
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A simple and efficient one-pot protocol is accomplished to access tricyclic spiro dihydrofurans (4) by the reaction of β-enamino ketones (1) and dimedone (2) in ethanol followed by sequential addition of N-chlorosuccinimide at ambient temperature for the first time. The selectivity in desired product formation in good yields is the advantage of this protocol. 相似文献