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1.
Rameshwar Prasad Pandit Seung Tae Kim Do Hyun Ryu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13561-13566
A cyclopropanation/intramolecular rearrangement initiated by the Michael addition of in situ generated ortho‐quinone methides (o‐QMs) has been developed for the enantioselective synthesis of 2‐aryl‐2,3‐dihydrobenzofurans containing two consecutive stereogenic centers, including a quaternary carbon atom. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction proceeded in excellent yields (up to 95 %) with excellent stereoselectivity (up to >99 ee, up to >20:1 d.r.). 相似文献
2.
Bec J. Roldan Travis A. Hammerstad Matthew S. Galliher Mitchell H. Keylor Prof. Dr. Derek A. Pratt Prof. Dr. Corey R. J. Stephenson 《Angewandte Chemie (International ed. in English)》2023,62(34):e202305801
A simple method for accessing trans-2,3-diaryl dihydrobenzofurans is reported. This approach leverages the equilibrium between quinone methide dimers and their persistent radicals. This equilibrium is disrupted by phenols that yield comparatively transient phenoxyl radicals, leading to cross-coupling between the persistent and transient radicals. The resultant quinone methides with pendant phenols rapidly cyclize to form dihydrobenzofurans (DHBs). This putative biomimetic access to dihydrobenzofurans provides superb functional group tolerance and a unified approach for the synthesis of resveratrol-based natural products. 相似文献
3.
Guozhu Li Qinzhe Liu Laxmaiah Vasamsetty Weicong Guo Jun Wang 《Angewandte Chemie (International ed. in English)》2020,59(9):3475-3479
A ruthenium(II)‐catalyzed asymmetric intramolecular hydroarylation assisted by a chiral transient directing group has been developed. A series of 2,3‐dihydrobenzofurans bearing chiral all‐carbon quaternary stereocenters have been prepared in remarkably high yields (up to 98 %) and enantioselectivities (up to >99 % ee). By this methodology, a novel asymmetric total synthesis of CB2 receptor agonist MDA7 has been successfully developed. 相似文献
4.
Asymmetric Hydroalkoxylation of Non‐Activated Alkenes: Titanium‐Catalyzed Cycloisomerization of Allylphenols at High Temperatures
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M. Sc. Johannes Schlüter M. Sc. Max Blazejak Dr. Florian Boeck Prof. Dr. Lukas Hintermann 《Angewandte Chemie (International ed. in English)》2015,54(13):4014-4017
The asymmetric catalytic addition of alcohols (phenols) to non‐activated alkenes has been realized through the cycloisomerization of 2‐allylphenols to 2‐methyl‐2,3‐dihydrobenzofurans (2‐methylcoumarans). The reaction was catalyzed by a chiral titanium–carboxylate complex at uncommonly high temperatures for asymmetric catalytic reactions. The catalyst was generated by mixing titanium isopropoxide, the chiral ligand (aS)‐1‐(2‐methoxy‐1‐naphthyl)‐2‐naphthoic acid or its derivatives, and a co‐catalytic amount of water in a ratio of 1:1:1 (5 mol % each). This homogeneous thermal catalysis (HOT‐CAT) gave various (S)‐2‐methylcoumarans with yields of up to 90 % and in up to 85 % ee at 240 °C, and in 87 % ee at 220 °C. 相似文献
5.
Chiral N,N′‐Dioxide–Scandium(III) Complex‐Catalyzed Asymmetric Friedel–Crafts Alkylation Reaction of ortho‐Hydroxybenzyl Alcohols with C3‐Substituted N‐Protected Indoles
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Jianfeng Zheng Dr. Lili Lin Li Dai Xiao Yuan Prof. Dr. Xiaohua Liu Prof. Dr. Xiaoming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18254-18258
The first Lewis acid catalyzed asymmetric Friedel–Crafts alkylation reaction of ortho‐hydroxybenzyl alcohols with C3‐substituted indoles is described. A chiral N,N′‐dioxide Sc(OTf)3 complex served not only to promote formation of ortho‐quinone methides (o‐QMs) in situ but also induced the asymmetry of the reaction. This methodology enables a novel activation of ortho‐hydroxybenzyl alcohols, thus affording the desired chiral diarylindol‐2‐ylmethanes in up to 99 % yield and 99 % ee. A range of functional groups were also tolerated under the mild reaction conditions. Moreover, this strategy gives concise access to enantioenriched indole‐fused benzoxocines. 相似文献
6.
A highly enantioselective three‐component hydroacyloxylation/1,4‐conjugate addition of ortho‐hydroxybenzyl alcohols, ynamides and carboxylic acids was developed under mild reaction conditions in the presence of a chiral N,N′‐dioxide/Sc(OTf)3 complex, which went through in situ generated ortho‐quinone methides with α‐acyloxyenamides, delivering a range of corresponding chiral α‐acyloxyenamides derivatives containing gem(1,1)‐diaryl skeletons in moderate to good yields with excellent ee values. The scale‐up experiment and further derivation showed the practicality of this catalytic system. In addition, a possible catalytic cycle and transition state model was proposed to elucidate the origin of the stereoselectivity based on X‐ray crystal structure of the α‐acyloxyenamide intermediate and product. 相似文献
7.
Brønsted Acid Catalyzed,Conjugate Addition of β‐Dicarbonyls to In Situ Generated ortho‐Quinone Methides—Enantioselective Synthesis of 4‐Aryl‐4H‐Chromenes
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M. Sc. Osama El‐Sepelgy M. Sc. Stefan Haseloff Dr. Santosh Kumar Alamsetti Prof. Dr. Christoph Schneider 《Angewandte Chemie (International ed. in English)》2014,53(30):7923-7927
We describe herein a catalytic, enantioselective process for the synthesis of 4H‐chromenes which are important structural elements of many natural products and biologically active compounds. A sequence comprising a conjugate addition of β‐diketones to in situ generated ortho‐quinone methides followed by a cyclodehydration reaction furnished 4‐aryl‐4H‐chromenes in generally excellent yields and high optical purity. A BINOL‐based chiral phosphoric acid was employed as a Brønsted acid catalyst which converted ortho‐hydroxy benzhydryl alcohols into hydrogen‐bonded ortho‐quinone methides and effected the carbon–carbon bond‐forming event with high enantioselectivity. 相似文献
8.
Ortho‐Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalyzed Cycloadditions with Unactivated Alkenes by Exclusive Activation of the Electrophile
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MSc. Chien‐Chi Hsiao Dr. Sadiya Raja MSc. Hsuan‐Hung Liao Prof. Dr. Magnus Rueping 《Angewandte Chemie (International ed. in English)》2015,54(19):5762-5765
An efficient method for the highly enantioselective synthesis of chiral chromanes bearing multiple stereogenic centers was developed. A chiral BINOL‐based N‐triflylphosphoramide proved to be an effective catalyst for the in situ generation of ortho‐quinone methides (o‐QMs) and their subsequent cycloaddition reaction with unactivated alkenes provided chromanes with excellent diastereo‐ and enantioselectivity. 相似文献
9.
Wenqiang Yang Yangyuan Liu Shasha Zhang Qian Cai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(30):8929-8932
O‐Heterocyclic structures such as 2,3‐dihydrobenzofurans are key motifs in many natural compounds and pharmaceuticals. Enantioselective formation of chiral dihydrobenzofurans and analogues was achieved through a copper‐catalyzed desymmetrization strategy with a chiral cyclic 1,2‐diamine. A broad range of substrates are compatible with this CuI‐diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions. 相似文献
10.
Xianghui Liu Kai Wang Prof. Yan Liu Prof. Can Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(2):735-739
Reported in this work is a water triggered chemo-divergent enantioselective spiro-annulation and cascade reaction of ortho-quinone methides (o-QMs) with α-thiocyanato indanones catalyzed by a chiral organic base. In the case of spiro-annulation, the use of trace amount of water as additive is critical to achieve high enantioselectivity (up to 96 % ee). We found that a cascade reaction was enabled by just tuning the ratio of water in solvent. Accordingly, two new highly efficient asymmetric reactions for the divergent synthesis of spiro- and fused-indanone scaffolds with excellent enantioselectivities (up to 99 % ee) were developed. Mechanistic investigations suggest that interfacial hydrogen bonding may play an important role in achieving the switchable reaction pathways. 相似文献
11.
Dr. Valmik S. Shinde Dr. Manoj V. Mane Prof. Luigi Cavallo Prof. Dr. Magnus Rueping 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8308-8313
A new catalytic enantioselective hydroarylation of unactivated olefins is developed that provides rapid access to functionalized chiral dihydrobenzofurans with good yields and excellent enantioselectivities. Simple aromatic ketones or amides act as a directing group allowing the regioselective reaction at the more hindered ortho position. Tertiary benzylic stereocenters are obtained directly under mild reaction conditions and with complete atom economy from readily available starting materials. 相似文献
12.
Asymmetric Brønsted Acid Catalyzed Substitution of Diaryl Methanols with Thiols and Alcohols for the Synthesis of Chiral Thioethers and Ethers
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Adisak Chatupheeraphat Hsuan‐Hung Liao Steffen Mader Makoto Sako Prof. Dr. Hiroaki Sasai Dr. Iuliana Atodiresei Prof. Dr. Magnus Rueping 《Angewandte Chemie (International ed. in English)》2016,55(15):4803-4807
An enantioselective addition of thiols and alcohols to aza‐ortho‐quinone methides, starting from diaryl methanols, was developed. The asymmetric additions occur under mild reaction conditions in the presence of chiral phosphoric acids and furnish the corresponding adducts with excellent yields and enantioselectivities. 相似文献
13.
Copper‐Catalyzed Intramolecular Desymmetric Aryl CO Coupling for the Enantioselective Construction of Chiral Dihydrobenzofurans and Dihydrobenzopyrans
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Wenqiang Yang Yangyuan Liu Shasha Zhang Prof. Dr. Qian Cai 《Angewandte Chemie (International ed. in English)》2015,54(30):8805-8808
O‐Heterocyclic structures such as 2,3‐dihydrobenzofurans are key motifs in many natural compounds and pharmaceuticals. Enantioselective formation of chiral dihydrobenzofurans and analogues was achieved through a copper‐catalyzed desymmetrization strategy with a chiral cyclic 1,2‐diamine. A broad range of substrates are compatible with this CuI‐diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions. 相似文献
14.
Takeshi Nagai Takahiro Uno Masataka Kubo Takahito Itoh 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):466-479
Asymmetric anionic polymerizations of 7‐cyano‐7‐alkoxycarbonyl‐1,4‐benzoquinone methides ( 1 ) with various alkoxy groups were performed using chiral initiators such as lithium isopropylphenoxide (iPrPhOLi)/(S)‐(–)‐2,2′‐isopropylidene‐bis(4‐phenyl‐2‐oxazoline) ((–)‐PhBox) and lithium isopropylphenoxide (iPrPhOLi)/(–)‐sparteine ((–)‐Sp) to investigate the effect of the alkoxy groups of alkoxycarbonyl substituent in the monomers 1 and chiral ligands of chiral initiators on the control of chiral center in the formation of polymers. Molar optical rotation values of the polymers were significantly dependent upon alkoxy groups, and the polymers with higher molar optical rotation were obtained in monomers with primary alkoxy groups. The asymmetric anionic oligomerizations of the quinone methides having methoxy( 1a ), ethoxy( 1b ), and n‐propoxy( 1c ) groups with chiral initiators were carried out. Both 1‐mers and 2‐mers were isolated and their optical resolutions were performed to determine the extent of stereocontrol. High stereoselectivity was observed at the propagation reaction, but not at the initiation reaction. The effect of the counterion on the control of chiral center in the formation of the polymer was investigated in the asymmetric anionic polymerizations of 1b with iPrPhOM(M = Li, Na, K)/(–)‐Sp and iPrPhOM(M = Li, Na, K)/(–)‐PhBox initiators and discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
15.
An intramolecular, organocatalyzed Michael addition has been developed to obtain biologically important 2,3‐disubstituted cis‐2,3‐dihydrobenzofurans. By using mandelic acid salts of primary aminocatalysts, derived from cinchona alkaloids, the intramolecular cyclization reaction has been developed to proceed in high yield, with moderate to good diastereoselectivity, and up to 99 % ee. Based on the absolute configuration of the formed 2,3‐disubstituted‐cis‐2,3‐dihydrobenzofurans and by considering the observed substrate scope restrictions, a mechanistic rationalization has been presented. 相似文献
16.
Xian-Tao An Dr. Ji-Yuan Du Zhi-Long Jia Qing Zhang Ke-Yin Yu Yi-Zhou Zhang Dr. Xian-He Zhao Prof. Dr. Ran Fang Prof. Dr. Chun-An Fan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3803-3809
Palladium-catalyzed asymmetric [4+5] annulation of ortho-quinone methides (o-QMs) with substituted vinylethylene carbonates (VECs) is described for the first time, giving a novel enantioselective approach to chiral nine-membered benzoheterocycles. Based on this designed [4+5] annulation, an unprecedented silica gel-promoted tandem rearrangement reaction featuring a unique asymmetric aromatic Claisen rearrangement is explored at room temperature, offering a new method for asymmetric construction of all-carbon quaternary stereocenters embedded in chiral functionalized homoallylic alcohols. 相似文献
17.
Phosphoric Acid Catalyzed Asymmetric 1,6‐Conjugate Addition of Thioacetic Acid to para‐Quinone Methides
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Nan Dong Zhi‐Pei Zhang Dr. Xiao‐Song Xue Prof. Xin Li Prof. Jin‐Pei Cheng 《Angewandte Chemie (International ed. in English)》2016,55(4):1460-1464
An asymmetric 1,6‐conjugate addition of thioacetic acid with para‐quinone methides has been developed by using chiral phosphoric acid catalysis in the presence of water. A series of sulfur‐containing compounds were thus obtained in high yields with good to excellent enantioselectivities. Theoretical studies indicated that the water‐bridged proton transfer is a potentially favorable reaction pathway. An unprecedented O?H???π interaction between water and the aromatic nucleus of chiral phosphoric acid was discovered to contribute significantly to the stereocontrol in the catalysis. 相似文献
18.
Catalytic Asymmetric 1,6‐Conjugate Addition of para‐Quinone Methides: Formation of All‐Carbon Quaternary Stereocenters
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Dr. Zhaobin Wang Yuk Fai Wong Prof. Jianwei Sun 《Angewandte Chemie (International ed. in English)》2015,54(46):13711-13714
Described herein is a general and mild catalytic asymmetric 1,6‐conjugate addition of para‐quinone methides (p‐QMs), a class of challenging reactions with previous limited success. Benefiting from chiral Brønsted acid catalysis, which allows in situ formation of p‐QMs, our reaction expands the scope to general p‐QMs with various substitution patterns. It also enables efficient intermolecular formation of all‐carbon quaternary stereocenters with high enantioselectivity. 相似文献
19.
《Angewandte Chemie (International ed. in English)》2017,56(18):4936-4940
Herein, we describe the first catalytic asymmetric intramolecular [4+2] cycloaddition of in situ generated ortho‐quinone methides. In the presence of a confined chiral imidodiphosphoric acid catalyst, various salicylaldehydes react with dienyl alcohols to give transient ortho ‐quinone methide intermediates, which undergo an intramolecular [4+2] cycloaddition to provide highly functionalized furanochromanes and pyranochromanes in excellent diastereoselectivity and enantioselectivity. 相似文献
20.
Direct Synthesis of Benzofuro[2,3‐b]pyrroles through a Radical Addition/[3,3]‐Sigmatropic Rearrangement/Cyclization/Lactamization Cascade
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Dr. Masafumi Ueda Yuta Ito Yuki Ichii Maiko Kakiuchi Hiroko Shono Prof. Dr. Okiko Miyata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6763-6770
A straightforward synthetic method for the construction of benzofuro[2,3‐b]pyrrol‐2‐ones by a novel domino reaction through a radical addition/[3,3]‐sigmatropic rearrangement/cyclization/lactamization cascade has been developed. The domino reaction of O‐phenyl‐conjugated oxime ether with an alkyl radical allows the construction of two heterocycles with three stereogenic centers as a result of the formation of two C?C bonds, a C?O bond, and a C?N bond in a single operation, leading to pyrrolidine‐fused dihydrobenzofurans, which are not easily accessible by existing synthetic methods. Furthermore, asymmetric synthesis of benzofuro[2,3‐b]pyrrol‐2‐one derivatives through a diastereoselective radical addition reaction to a chiral oxime ether was also developed. 相似文献