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1.
Cobalt‐Catalyzed Diborylation of 1,1‐disubstituted Vinylarenes: A Practical Route to Branched gem‐Bis(boryl)alkanes
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Wei Jie Teo Prof. Dr. Shaozhong Ge 《Angewandte Chemie (International ed. in English)》2018,57(6):1654-1658
We report the first catalytic diborylation of 1,1‐disubstituted vinylarenes with pinacolborane using a cobalt catalyst generated from bench‐stable Co(acac)2 and xantphos. A wide range of 1,1‐disubstituted vinylarenes underwent this transformation to produce the corresponding gem‐bis(boryl)alkanes in modest to high yields. This cobalt‐catalyzed reaction can be readily conducted on a gram scale without the use of a dry box and represents a practical and effective approach to prepare a wide range of branched gem‐bis(boryl)alkanes. 相似文献
2.
A Copper(I)‐Catalyzed Enantioselective γ‐Boryl Substitution of Trifluoromethyl‐Substituted Alkenes: Synthesis of Enantioenriched γ,γ‐gem‐Difluoroallylboronates
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Dr. Ryoto Kojima Sota Akiyama Prof. Dr. Hajime Ito 《Angewandte Chemie (International ed. in English)》2018,57(24):7196-7199
The first catalytic enantioselective γ‐boryl substitution of CF3‐substituted alkenes is reported. A series of CF3‐substituted alkenes was treated with a diboron reagent in the presence of a copper(I)/Josiphos catalyst to afford the corresponding optically active γ,γ‐gem‐difluoroallylboronates in high enantioselectivity. The thus obtained products could be readily converted into the corresponding difluoromethylene‐containing homoallylic alcohols using highly stereospecific allylation reactions. 相似文献
3.
Qian Wang Chuanfa Ni Mingyou Hu Qiqiang Xie Qinghe Liu Shitao Pan Jinbo Hu 《Angewandte Chemie (International ed. in English)》2020,59(22):8507-8511
A Cu‐catalyzed gem‐bis(trifluoromethyl)olefination of α‐diazo esters, using TMSCF3 as the only fluorocarbon source, has been developed and provides an exquisite method to access gem‐bis(trifluoromethyl)alkenes. This unprecedented olefination process involves a carbene migratory insertion into “CuCF3” to generate the α‐CF3‐substituted organocopper species, which then undergoes β‐fluoride elimination and two consecutive addition‐elimination processes to give the desired products. The key to this efficient one‐pot C1‐to‐C3 synthetic protocol lies in the controllable double (over single and triple) trifluoromethylations of the gem‐difluoroalkene intermediates. 相似文献
4.
A general and efficient approach for the preparation of 1,3‐bis‐(boryl)alkanes is introduced. It is shown that readily generated vinylboron ate complexes react with commercially available ICH2Bpin to valuable 1,3‐bis‐(boryl)alkanes. The introduced transformation, which is experimentally easy to conduct, shows broad substrate scope and high functional‐group tolerance. Mechanistic studies reveal that the reaction does not proceed via radical intermediates. Instead, an unprecedented boronic ester induced sequential bis‐1,2‐migration cascade is suggested. 相似文献
5.
Tomoya Miura Naoki Oku Masahiro Murakami 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14762-14766
We report the highly diastereo‐ and enantioselective preparation of (E)‐δ‐boryl‐substituted anti‐homoallylic alcohols in two steps from terminal alkynes. This method consists of a cobalt(II)‐catalyzed 1,1‐diboration reaction of terminal alkynes with B2pin2 and a palladium(I)‐mediated asymmetric allylation reaction of the resulting 1,1‐di(boryl)alk‐1‐enes with aldehydes in the presence of a chiral phosphoric acid. Propyne, which is produced as the byproduct during petroleum refining, could be used as the starting material to construct homoallylic alcohols that are otherwise difficult to synthesize with high stereocontrol. 相似文献
6.
Jing Qi Feng‐Lian Zhang Ji‐Kang Jin Qiang Zhao Bin Li Lin‐Xuan Liu Yi‐Feng Wang 《Angewandte Chemie (International ed. in English)》2020,59(31):12876-12884
Radical borylation using N‐heterocyclic carbene (NHC)‐BH3 complexes as boryl radical precursors has emerged as an important synthetic tool for organoboron assembly. However, the majority of reported methods are limited to reaction modes involving carbo‐ and/or hydroboration of specific alkenes and alkynes. Moreover, the generation of NHC‐boryl radicals relies principally on hydrogen atom abstraction with the aid of radical initiators. A distinct radical generation method is reported, as well as the reaction pathways of NHC‐boryl radicals enabled by photoredox catalysis. NHC‐boryl radicals are generated via a single‐electron oxidation and subsequently undergo cross‐coupling with the in‐situ‐generated radical anions to yield gem‐difluoroallylboronates. A photoredox‐catalyzed radical arylboration reaction of alkenes was achieved using cyanoarenes as arylating components from which elaborated organoborons were accessed. Mechanistic studies verified the oxidative formation of NHC‐boryl radicals through a single‐electron‐transfer pathway. 相似文献
7.
Binlin Zhao Zexian Li Yixiao Wu Yandong Wang Jiasheng Qian Yu Yuan Zhuangzhi Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9548-9552
A series of in situ formed alkenyl diboronate complexes from alkenyl Grignard reagents (commercially available or prepared from alkenyl bromides and Mg) with B2Pin2 (bis(pinacolato)diboron) react with diverse alkyl halides by a Ru photocatalyst to give various gem‐bis(boryl)alkanes. Alkyl radicals add efficiently to the alkenyl diboronate complexes, and the adduct radical anions undergo radical‐polar crossover, specifically, a 1,2‐boryl‐anion shift from boron to the α‐carbon sp2 center. This transformation shows good functional‐group compatibility and can serve as a powerful synthetic tool for late‐stage functionalization in complex compounds. Measurements of the quantum yield reveal that a radical‐chain mechanism is operative in which the alkenyl diboronates acts as reductive quencher for the excited state of the photocatalyst. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(31):9339-9344
A palladium‐catalyzed asymmetric synthesis of silicon‐stereogenic 5,10‐dihydrophenazasilines was developed that proceeds via an unprecedented enantioselective 1,5‐palladium migration. High enantioselectivity was achieved by employing 4,4′‐bis(trimethylsilyl) (R )‐Binap as the chiral ligand, and a series of mechanistic investigations were carried out to probe the catalytic cycle of this process. 相似文献
9.
Clair Bilton Judith A. K. Howard N. N. Laxmi Madhavi Gautam R. Desiraju Frank H. Allen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1356-1358
The title compounds, C8H10O2, (I), and C12H14O2, (II), occurred as by‐products in the controlled synthesis of a series of bis(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P21/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclohexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent molecules, in the cyclohexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, Cmethylene—H?O(H) and Cmethyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here. 相似文献
10.
Highly Enantioselective Iron‐Catalyzed cis‐Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an FeIII‐OOH Reactive Intermediate
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Dr. Chao Zang Dr. Yungen Liu Dr. Zhen‐Jiang Xu Chun‐Wai Tse Dr. Xiangguo Guan Jinhu Wei Dr. Jie‐Sheng Huang Prof. Dr. Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2016,55(35):10253-10257
The development of environmentally benign catalysts for highly enantioselective asymmetric cis‐dihydroxylation (AD) of alkenes with broad substrate scope remains a challenge. By employing [FeII(L)(OTf)2] (L=N,N′‐dimethyl‐N,N′‐bis(2‐methyl‐8‐quinolyl)‐cyclohexane‐1,2‐diamine) as a catalyst, cis‐diols in up to 99.8 % ee with 85 % isolated yield have been achieved in AD of alkenes with H2O2 as an oxidant and alkenes in a limiting amount. This “[FeII(L)(OTf)2]+H2O2” method is applicable to both (E)‐alkenes and terminal alkenes (24 examples >80 % ee, up to 1 g scale). Mechanistic studies, including 18O‐labeling, UV/Vis, EPR, ESI‐MS analyses, and DFT calculations lend evidence for the involvement of chiral FeIII‐OOH active species in enantioselective formation of the two C?O bonds. 相似文献
11.
Jiawang Liu Ji Yang Francesco Ferretti Ralf Jackstell Matthias Beller 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(14):4738-4742
The first catalyst for the alkoxycarbonylation of gem‐difluoroalkenes is described. This novel catalytic transformation proceeds in the presence of Pd(acac)2/1,2‐bis((di‐tert‐butylphosphan‐yl)methyl)benzene (btbpx) ( L4 ) and allows for an efficient and straightforward access to a range of difluoromethylated esters in high yields and regioselectivities. The synthetic utility of the protocol is showcased in the practical synthesis of a Cyclandelate analogue using this methodology as the key step. 相似文献
12.
Opportune gem‐Silylborylation of Carbonyl Compounds: A Modular and Stereocontrolled Entry to Tetrasubstituted Olefins
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Enrico La Cascia Dr. Ana B. Cuenca Dr. Elena Fernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18737-18741
An easy access to highly versatile gem‐silylboronate synthons is achieved by means of a new olefination reagent, HC(Bpin)2(SiMe3). Subsequent silicon or boron‐based selective functionalization allows for the modular and stereocontrolled synthesis of all‐carbon tetrasubstituted alkenes. A particular attraction of this approach is the iododesilylation reaction, which becomes a pivotal tool for C?Si functionalization. 相似文献
13.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11742-11746
Reported herein is an efficient copper(I)‐catalytic system for the diastereo‐ and enantioselective 1,2‐addition of 1,1‐bis[(pinacolato)boryl]alkanes to protected imines to afford synthetically valuable enantioenriched β‐aminoboron compounds bearing contiguous stereogenic centers. The reaction exhibits a broad scope with respect to protected imines and 1,1‐bis[(pinacolato)boryl]alkanes, thus providing β‐aminoboronate esters with excellent diastereo‐ and enantioselectivity. The synthetic utility of the obtained β‐aminoboronate ester was also demonstrated. 相似文献
14.
AgF‐Mediated Fluorinative Cross‐Coupling of Two Olefins: Facile Access to α‐CF3 Alkenes and β‐CF3 Ketones
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Dr. Bing Gao Dr. Yanchuan Zhao Prof. Dr. Jinbo Hu 《Angewandte Chemie (International ed. in English)》2015,54(2):638-642
A AgF‐mediated fluorination with a concomitant cross‐coupling between a gem‐difluoroolefin and a non‐fluorinated olefin is reported. This highly efficient method provides facile access to both α‐CF3 alkenes and β‐CF3 ketones, which otherwise remain challenging to be directly prepared. The application of this method is further demonstrated by the synthesis of bioactive isoxazoline derivatives. This approach represents a conceptually novel route to trifluoromethylated compounds that combines the in situ generation of the CF3 moiety and a C? H functionalization in a single reaction system. 相似文献
15.
Ryosuke Sakae Dr. Koji Hirano Prof. Dr. Tetsuya Satoh Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2015,54(2):613-617
A copper‐catalyzed aminoboration of bicyclic alkenes, including oxa‐ and azabenzonorbornadienes, has been developed. With this method, amine and boron moieties are simultaneously introduced at an olefin with exo selectivity. Subsequent stereospecific transformations of the boryl group can provide oxygen‐ and nitrogen‐rich cyclic molecules with motifs that may be found in natural products or pharmaceutically active compounds. Moreover, a catalytic asymmetric variant of this transformation was realized by using a copper complex with a chiral bisphosphine ligand, namely (R,R)‐Ph‐BPE. 相似文献
16.
Michael G. Edwards David S. Pugh Adrian C. Whitwood Richard J. K. Taylor 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):o39-o41
The reaction between dibenzylideneacetone (dba) and triisopropyl sulfoxonium tetrafluoroborate has been reinvestigated. The stereochemistry of the major diasteromeric bis(gem‐dimethylcyclopropane) adduct has now been assigned as [(1RS,3RS)‐2,2‐dimethyl‐3‐phenylcyclopropyl][(1SR,3SR)‐2,2‐dimethyl‐3‐phenylcyclopropyl]methanone, C23H26O, by X‐ray crystallographic studies on a twinned crystal. The asymmetric unit contains two molecules of the adduct, the conformations of which differ in the orientation of the phenyl ring relative to the adjacent cyclopropanated double bond. The carbonyl groups of each adduct are aligned approximately along the a axis and in opposite directions to each other. The molecules pack to give a sinusoidal pattern along the b axis. This is the first acyclic bis(dimethylcyclopropyl) ketone for which an X‐ray crystal structure determination has been reported, and is also the first bis‐cyclopropanated dba analogue. The knowledge that the major diastereomer has the meso structure (and therefore the confirmation that the minor isomer is the racemate) will prove invaluable in future studies to utilize bis(dimethylcyclopropyl) ketones as reagents, in rearrangement processes, and as potential ligands and ligand precursors in organometallic chemistry. 相似文献
17.
Xiao‐Wei Liang Yunlong Zhao Xu‐Ge Si Meng‐Meng Xu Jia‐Hao Tan Zhi‐Mao Zhang Cheng‐Gong Zheng Chao Zheng Quan Cai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14704-14709
An enantioselective chemical synthesis of arene cis‐dihydrodiols has been realized from 2‐pyrones through sequential ytterbium‐catalyzed asymmetric inverse‐electron‐demand Diels–Alder (IEDDA) reaction of 2‐pyrones and retro‐Diels–Alder extrusion of CO2. By using this strategy, a series of substituted arene cis‐dihydrodiols can be obtained efficiently with high enantioselectivity (>99 % ee in many cases). Based on this strategy, efficient and concise asymmetric total syntheses of (+)‐MK7607 and 1‐epi‐(+)‐MK7607 were accomplished. 相似文献
18.
Congyu Li Jing‐Mei Yuan Wenqiang Chen Yimiao He Jun Huang Yanmin Huang Qi Xiao Jiarong Sheng Chusheng Huang 《化学:亚洲杂志》2019,14(15):2584-2587
Defluorinative C(sp3)?P bond formation of α‐trifluoromethyl alkenes with phosphine oxides or phosphonates have been achieved under catalyst‐ and oxidant‐free conditions, giving phosphorylation gem‐difluoroalkenes as products. α‐Trifluoromethyl alkenes bearing various of aryl substituents such as halogen, cyano, ester and heterocyclic groups are available in this transformation. The results of control experiments demonstrated that the mechanism of dehydrogenative/defluorinative cross‐coupling reactions was not a radical route, but might be an SN2′ process involving phosphine oxide anion. 相似文献
19.
A series of new N‐aryl‐α,β‐disubstituted amides (gem or E1; trans or E2) were synthesized in good yields by carbonylative addition of aniline derivatives 1a–f to aromatic alkynes 2a,b catalyzed by Pd(OAc)2 and 1,3‐bis(diphenylphosphino)propane. The catalytic synthesis of tertiary α,β‐unsaturated amides was also successfully achieved. Traces of products were observed in the absence of p‐toluenesulfonic acid used as an additive. The reaction is sensitive to the type of phosphine ligand and solvent. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
20.