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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7587-7591
The first asymmetric [3+1]‐cycloaddition was successfully achieved by copper(I) triflate/double‐sidearmed bisoxazoline complex catalyzed reactions of β‐triisopropylsilyl‐substituted enoldiazo compounds with sulfur ylides. This methodology delivered a series of chiral cyclobutenes in good yields with high enantio‐ and diastereoselectivities (up to 99 % ee , and >20:1 d.r.). Additionally, the [3+1]‐cycloaddition of catalytically generated metallo‐enolcarbenes was successfully extended to reaction with a stable benzylidene dichlororuthenium complex. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(10):2714-2718
An amide‐thiourea compound, operating through a novel ion pairing mechanism, is an efficient organocatalyst for the asymmetric reaction of homophthalic anhydride with imines. N ‐aryl and N ‐alkyl imines readily undergo formal [4+2] cycloaddition to provide lactams with high levels of enantio‐ and diastereoselectivity. The nature of the key chiral ion pair intermediate was elucidated by DFT calculations. 相似文献
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Shulin Ge Weidi Cao Tengfei Kang Bowen Hu Hang Zhang Zhishan Su Xiaohua Liu Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4057-4061
The enantioselective tandem reaction of β,γ‐unsaturated α‐ketoesters with β‐alkynyl ketones was realized by a bimetallic catalytic system of achiral AuΙΙΙ salt and chiral N,N′‐dioxide‐MgΙΙ complex. The cycloisomerization of β‐alkynyl ketone and asymmetric intermolecular [4+2] cycloaddition with β,γ‐unsaturated α‐ketoesters subsequently occurred, providing an efficient and straightforward access to chiral multifunctional 6,6‐spiroketals in up to 97 % yield, 94 % ee and >19/1 d.r. Besides, a catalytic cycle was proposed based on the results of control experiments. 相似文献
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Prof. Dr. Barry M. Trost Dr. Zhijun Zuo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1259-1263
A novel Pd0-catalyzed asymmetric [4+3] annulation reaction of two readily accessible starting materials has been developed for building seven-membered heterocyclic architectures. The potential [3+2] side pathway could be suppressed though fine tuning of the conditions. A broad scope of cycloaddition donors and acceptors participated in the transformation with excellent chemo-, regio-, diastereo-, and enantioselectivtities, leading to valuable tetrahydroazepines and benzo[b]oxepines. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(40):12460-12464
Highly selective divergent cycloaddition reactions of enoldiazo compounds and α‐diazocarboximides catalyzed by copper(I) or dirhodium(II) have been developed. With tetrakis(acetonitrile)copper(I) tetrafluoroborate as the catalyst epoxypyrrolo[1,2‐a]azepine derivatives were prepared in good yields and excellent diastereoselectivities through the first reported [3+3]‐cycloaddition of a carbonyl ylide. Use of Rh2(pfb)4 or Rh2(esp)2 directs the reactants to regioselective [3+2]‐cycloaddition generating cyclopenta[2,3]pyrrolo[2,1‐b]oxazoles with good yields and excellent diastereoselectivities. 相似文献
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Ke Xu Wenchang Li Shaoheng Zhu Tingshun Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17789-17794
Atroposelective arene formation is an efficient method to build axially chiral molecules with multi‐substituted arenes. Reported here is an organocatalyzed atroposelective arene formation reaction by an N‐heterocyclic carbene (NHC) catalyzed formal [4+2] cycloaddition of conjugated dienals and α‐aryl ketones. This study expands the synthetic potential of NHC organocatalysis and provides a competitive pathway for the synthesis of axially chiral ligands, catalysts, and other functional molecules. 相似文献
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Qiang Cheng Jia‐Hao Xie Yue‐Cheng Weng Shu‐Li You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5795-5799
Dearomatization of anthranils with vinylcyclopropanes (VCPs) by Pd‐catalyzed [4+3] cyclization reaction has been realized. In the presence of a catalytic amount of borane as an activator, bridged cyclic products were obtained in good to excellent yields with excellent stereoselectivities. By introducing a chiral PHOX ligand ( L5 ), asymmetric dearomatization reactions of anthranils with vinylcyclopropanes proceeded with excellent enantioselectivity. Borane plays a key role for the reactivity, likely owing to the formation of a borane–anthranil complex which has been confirmed by NMR experiments. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(7):1890-1894
We report herein the asymmetric coupling of flow‐generated unstabilized diazo compounds and propargylated amine derivatives, using a new pyridinebis(imidazoline) ligand, a copper catalyst and base. The reaction proceeds rapidly, generating chiral allenes in 10–20 minutes with high enantioselectivity (89–98 % de/ee), moderate yields and a wide functional group tolerance. 相似文献
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Ronald Nelson Moiss Gulías Jos L. Mascareas Fernando Lpez 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(46):14571-14575
A practical synthesis of (−)‐englerin A was accomplished in 17 steps and 11 % global yield from commercially available achiral precursors. The key step consists of a platinum‐catalyzed [4C+3C] allenediene cycloaddition that directly delivers the trans‐fused guaiane skeleton with complete diastereoselectivity. The high enantioselectivity (99 % ee) stems from an asymmetric ruthenium‐catalyzed transfer hydrogenation of a readily assembled diene–ynone. The synthesis also features a highly stereoselective oxygenation, and a late‐stage cuprate alkylation that enables the preparation of previously inaccessible structural analogues. 相似文献
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Nicoletta Brindani Gloria Rassu Luca Dell'Amico Vincenzo Zambrano Luigi Pinna Claudio Curti Andrea Sartori Lucia Battistini Giovanni Casiraghi Giorgio Pelosi Daniela Greco Franca Zanardi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(25):7494-7498
A direct aminocatalytic synthesis has been developed for the chemo‐, regio‐, diastereo‐, and enantioselective construction of densely substituted polycyclic carbaldehydes containing fused cyclohexadiene rings. The chemistry utilizes, for the first time, remotely enolizable π‐extended allylidenemalononitriles as electron‐rich 1,3‐diene precursors in a direct eliminative [4+2] cycloaddition with both aromatic and aliphatic α,β‐unsaturated aldehydes. The generality of the process is demonstrated by approaching 6,6‐, 5,6‐, 7,6‐, 6,6,6‐, and 6,5,6‐fused ring systems, as well as biorelevant steroid‐like 6,6,6,6,5‐ and 6,6,6,5,6‐rings. A stepwise reaction mechanism for the key [4+2] addition is proposed as a domino bis‐vinylogous Michael/Michael/retro‐Michael reaction cascade. The utility of the malononitrile moiety as traceless activating group of the dicyano nucleophilic substrates is demonstrated. 相似文献