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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(43):13504-13508
The first catalytic asymmetric synthesis of highly functionalized difluoromethylated cyclopropanes is described. The method, based on a rhodium‐catalyzed cyclopropanation of difluoromethylated olefins, gives access to a broad range of cyclopropanes bearing ester, ketone, or nitro functional groups. By using Rh2((S )‐BTPCP)4 as a catalyst, the corresponding products were obtained in high yields and high diastereo‐ and enantioselectivities (up 20:1 d.r. and 99 % ee ). This methodology allowed preparation of enantioenriched difluoromethylcyclopropanes for the first time. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(14):4003-4008
Reported herein is an exceptional chemoselective ring‐opening/C(sp3)−C(sp3) bond formation in the copper(I)‐catalyzed reaction of cyclopropanols with diazo esters. The conventional O−H insertion product is essentially suppressed by judicious choice of reaction conditions. DFT calculations provide insights into the reaction mechanism and the rationale for this unusual chemoselectivity. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8991-8995
The 2‐substituted piperidine core is found in drugs (18 FDA‐approved drugs), however, their spirocyclic analogues remain unknown. Described here is the synthesis of spirocyclic analogues for 2‐substituted piperidines and a demonstration of their validation in drug discovery. 相似文献
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Marc Montesinos‐Magraner Matteo Costantini Rodrigo Ramírez‐Contreras Michael E. Muratore Magnus J. Johansson Abraham Mendoza 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(18):5991-5996
Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates, and reagents, even when targeting similar compounds. This approach slows down discovery and limits available chemical space. Introduced herein is a practical and versatile diazocompound and its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. The redox‐active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect allowed the asymmetric cyclopropanation of various olefins, including unfunctionalized aliphatic alkenes, that enables the three‐step total synthesis of (?)‐dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally differentiated diazocompounds are viable and advantageous equivalents of single‐carbon chirons. 相似文献
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Qixue Qin Xiao Luo Jialiang Wei Yuchao Zhu Xiaojin Wen Song Song Ning Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(13):4420-4424
A novel activation of acetonitrile for the construction of cyclobutenones by [2+2] cyclization was developed. Acetonitrile is utilized for the first time as two‐carbon (C2) cyclization building block. The present protocol successfully inhibits the competitive cycloaddition with the C≡N bond of acetonitrile, but enables the in situ formation of an unsaturated carbon–carbon bond and the subsequent cycloaddition as a C2 unit. This chemistry features simple reaction conditions, high chemoselectivities, wide substrate scope, and offers a new and practical approach to cyclobutenones and cyclobuteneimines. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8793-8797
Previously reported was that cis‐ene‐vinylcyclopropanes (cis‐ene‐VCPs) underwent Rh‐catalyzed [5+2] reaction to give 5,7‐fused bicyclic products, where vinylcyclopropane (VCP) acts as five‐carbon synthon. Unfortunately, this reaction had very limited scope. Replacing the 2π component of cis‐ene‐VCPs to allene moiety, the corresponding cis‐allene‐VCPs did not undergo the expected normal [5+2] cycloaddition to give 5,7‐fused bicyclic products. Instead, the challenging bicyclo[4.3.1]decane skeleton was obtained via an unprecedented bridged [5+2] cycloaddition. DFT calculations were applied to understand why this bridged [5+2] reaction is favored over the anticipated but not realized normal [5+2] reaction. 相似文献
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