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1.
Baihua Ye Dr. Pavel A. Donets Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2014,53(2):507-511
Metal‐catalyzed functionalizations at the ortho position of a directing group have become an efficient bond‐forming strategy. A wide range of transformations that employ Cp*RhIII catalysts have been described, but despite their synthetic potential, enantioselective variants that use chiral versions of the Cp* ligand remain scarce (Cp*=pentamethyl cyclopentadienyl). Cyclopentadienyl compounds with an atropchiral biaryl backbone are shown to be suitable ligands for the efficient intramolecular enantioselective hydroarylation of aryl hydroxamates. Dihydrofurans that bear methyl‐substituted quaternary stereocenters are thus obtained by C? H functionalization under mild conditions. 相似文献
2.
Asymmetric Synthesis of Isoindolones by Chiral Cyclopentadienyl‐Rhodium(III)‐Catalyzed CH Functionalizations 下载免费PDF全文
Baihua Ye Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2014,53(30):7896-7899
Directed Cp*RhIII‐catalyzed carbon–hydrogen (C? H) bond functionalizations have evolved as a powerful strategy for the construction of heterocycles. Despite their high value, the development of related asymmetric reactions is largely lagging behind due to a limited availability of robust and tunable chiral cyclopentadienyl ligands. Rhodium complexes comprising a chiral Cp ligand with an atropchiral biaryl backbone enables an asymmetric synthesis of isoindolones from arylhydroxamates and weakly alkyl donor/acceptor diazo derivatives as one‐carbon component under mild conditions. The complex guides the substrates with a high double facial selectivity yielding the chiral isoindolones in good yields and excellent enantioselectivities. 相似文献
3.
Asymmetric Organocatalytic Direct C(sp2)H/C(sp3)H Oxidative Cross‐Coupling by Chiral Iodine Reagents 下载免费PDF全文
Hua Wu Yu‐Ping He Lue Xu Dong‐Yang Zhang Prof. Liu‐Zhu Gong 《Angewandte Chemie (International ed. in English)》2014,53(13):3466-3469
An asymmetric organocatalytic direct C? H/C? H oxidative coupling reaction of N1,N3‐diphenylmalonamides has been well established by using chiral organoiodine compounds as catalysts, wherein four C? H bonds were stereoselectively functionalized to give structurally diverse spirooxindoles with high levels of enantioselectivity. More importantly, the findings indicated that chiral hypervalent organoiodine reagents can serve as alternative catalysts for the creation of enantioselective functionalization of inactive C? H bonds. 相似文献
4.
Michael C. Haibach Prof. Dr. Daniel Seidel 《Angewandte Chemie (International ed. in English)》2014,53(20):5010-5036
Known for over a century, reactions that involve intramolecular hydride‐transfer events have experienced a recent resurgence. Undoubtedly responsible for the increased interest in this research area is the realization that hydride shifts represent an attractive avenue for C? H bond functionalization. The redox‐neutral nature of these complexity‐enhancing transformations makes them ideal for sustainable reaction development. This Review summarizes recent progress in this field while highlighting key historical contributions. 相似文献
5.
Corrigendum: Diastereo‐ and Enantioselective Intramolecular C(sp3)H Arylation for the Synthesis of Fused Cyclopentanes 下载免费PDF全文
Dr. Nicolas Martin Cathleen Pierre Dr. Michaël Davi Dr. Rodolphe Jazzar Prof. Dr. Olivier Baudoin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12341-12341
6.
Chiral γ‐Lactams by Enantioselective Palladium(0)‐Catalyzed Cyclopropane Functionalizations 下载免费PDF全文
Julia Pedroni Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2015,54(40):11826-11829
Cyclopropanes fused to pyrrolidines are important structural features found in a number of marketed drugs and development candidates. Typically, their synthesis involves the cyclopropanation of a dihydropyrrole precursor. Reported herein is a complementary approach which employs a palladium(0)‐catalyzed C? H functionalization of an achiral cyclopropane to close the pyrrolidine ring in an enantioselective manner. In contrast to aryl–aryl couplings, palladium(0)‐catalyzed C? H functionalizations involving the formation of C(sp3)? C(sp3) bonds of saturated heterocycles are very scarce. The presented strategy yields cyclopropane‐fused γ‐lactams from chloroacetamide substrates. A bulky Taddol phosphonite ligand in combination with adamantane‐1‐carboxylic acid as a cocatalyst provides the γ‐lactams in excellent yields and enantioselectivities. 相似文献
7.
Donghyeon Gwon Donggun Lee Jiyu Kim Dr. Sehoon Park Prof. Dr. Sukbok Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12421-12425
Direct C?H amidation of arylphosphoryl compounds has been developed by using an IrIII catalyst system under mild conditions. A wide range of substrates could be employed with high functional‐group tolerance. This procedure was successfully applied for the first time to the asymmetric reaction giving rise to a P‐chirogenic center with a high diastereomeric ratio of up to 19:1 (90 % de). 相似文献
8.
Alkene Isomerization–Hydroarylation Tandem Catalysis: Indole C2‐Alkylation with Aryl‐Substituted Alkenes Leading to 1,1‐Diarylalkanes 下载免费PDF全文
A cobalt‐N‐heterocyclic carbene catalyst generated from CoBr2, imidazolium salt, and cyclohexylmagnesium bromide was found to promote the imine‐directed C2‐alkylation of indoles with nonconjugated arylalkenes through a tandem alkene isomerization–hydroarylation process, affording 1,1‐diarylalkanes with exclusive regioselectivity. The feasibility of the tandem catalysis was demonstrated for allyl‐, homoallyl‐, and bishomoallylbenzene derivatives. The catalytic system is also applicable to a variety of β‐substituted styrene derivatives. Mechanistic experiments using deuterium‐labeled indole substrate and Grignard reagent provided insight into the cobalt‐mediated C? H activation step, which likely involves exchange of the C2‐hydrogen atom of the former and the β‐hydrogen atoms of the latter. 相似文献
9.
Catalytic 1,4‐Rhodium(III) Migration Enables 1,3‐Enynes to Function as One‐Carbon Oxidative Annulation Partners in CH Functionalizations 下载免费PDF全文
Dr. David J. Burns Prof. Hon Wai Lam 《Angewandte Chemie (International ed. in English)》2014,53(37):9931-9935
1,3‐Enynes containing allylic hydrogens cis to the alkyne are shown to act as one‐carbon partners, rather than two‐carbon partners, in various rhodium‐catalyzed oxidative annulations. The mechanism of these unexpected transformations is proposed to occur through double C? H activation, involving a hitherto rare example of the 1,4‐migration of a RhIII species. This phenomenon is general across a variety of substrates, and provides a diverse range of heterocyclic products. 相似文献
10.
11.
Direct α‐Arylation of Ethers through the Combination of Photoredox‐Mediated CH Functionalization and the Minisci Reaction 下载免费PDF全文
Dr. Jian Jin Prof. Dr. David W. C. MacMillan 《Angewandte Chemie (International ed. in English)》2015,54(5):1565-1569
The direct α‐arylation of cyclic and acyclic ethers with heteroarenes has been accomplished through the design of a photoredox‐mediated C? H functionalization pathway. Transiently generated α‐oxyalkyl radicals, produced from a variety of widely available ethers through hydrogen atom transfer (HAT), were coupled with a range of electron‐deficient heteroarenes in a Minisci‐type mechanism. This mild, visible‐light‐driven protocol allows direct access to medicinal pharmacophores of broad utility using feedstock substrates and a commercial photocatalyst. 相似文献
12.
Palladium–N‐Heterocyclic Carbene (NHC)‐Catalyzed Asymmetric Synthesis of Indolines through Regiodivergent C(sp3)H Activation: Scope and DFT Study 下载免费PDF全文
Dmitry Katayev Dr. Evgeny Larionov Dr. Masafumi Nakanishi Dr. Céline Besnard Prof. Dr. E. Peter Kündig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15021-15030
Two bulky, chiral, monodentate N‐heterocyclic carbene ligands were applied to palladium‐catalyzed asymmetric C?H arylation to incorporate C(sp3)?H bond activation. Racemic mixtures of the carbamate starting materials underwent regiodivergent reactions to afford different trans‐2,3‐substituted indolines. Although this CAr?Calkyl coupling requires high temperatures (140–160 °C), chiral induction is high. This regiodivergent reaction, when carried out with enantiopure starting materials, can lead to single structurally different enantiopure products, depending on the catalyst chirality. The C?H activation at a tertiary center was realized only in the case of a cyclopropyl group. No C?H activation takes place alpha to a tertiary center. A detailed DFT study is included and analyses of methyl versus methylene versus methine C?H activation is used to rationalize experimentally observed regio‐ and enantioselectivities. 相似文献
13.
Catalytic Asymmetric Functionalization of Aromatic CH Bonds by Electrophilic Trapping of Metal‐Carbene‐Induced Zwitterionic Intermediates 下载免费PDF全文
Shikun Jia Dr. Dong Xing Dan Zhang Prof. Dr. Wenhao Hu 《Angewandte Chemie (International ed. in English)》2014,53(48):13098-13101
Asymmetric functionalization of aromatic C? H bonds of N,N‐disubstituted anilines with diazo compounds and imines is reported for the efficient construction of α,α‐diaryl benzylic quaternary stereocenters in good yields with high diastereoselectivities and excellent enantioselectivities. This RhII/chiral phosphoric acid cocatalyzed transformation is proposed to proceed through a metal‐carbene‐induced zwitterionic intermediate which undergoes electrophilic trapping. To the best of our knowledge, this is the first asymmetric example of metal carbene‐induced intermolecular functionalization of aryl C? H bonds. 相似文献
14.
First Principles (DFT) Characterization of RhI/dppp‐Catalyzed CH Activation by Tandem 1,2‐Addition/1,4‐Rh Shift Reactions of Norbornene to Phenylboronic Acid 下载免费PDF全文
Prof. Dr. Eric Assen B. Kantchev Surya R. Pangestu Dr. Feng Zhou Dr. Michael B. Sullivan Prof. Hai‐Bin Su 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15625-15634
The C?H activation in the tandem, “merry‐go‐round”, [(dppp)Rh]‐catalyzed (dppp=1,3‐bis(diphenylphosphino)propane), four‐fold addition of norborene to PhB(OH)2 has been postulated to occur by a C(alkyl)?H oxidative addition to square‐pyramidal RhIII?H species, which in turn undergoes a C(aryl)?H reductive elimination. Our DFT calculations confirm the RhI/RhIII mechanism. At the IEFPCM(toluene, 373.15 K)/PBE0/DGDZVP level of theory, the oxidative addition barrier was calculated to be 12.9 kcal mol?1, and that of reductive elimination was 5.0 kcal mol?1. The observed selectivity of the reaction correlates well with the relative energy barriers of the cycle steps. The higher barrier (20.9 kcal mol?1) for norbornyl–Rh protonation ensures that the reaction is steered towards the 1,4‐shift (total barrier of 16.3 kcal mol?1), acting as an equilibration shuttle. The carborhodation (13.2 kcal mol?1) proceeds through a lower barrier than the protonation (16.7 kcal mol?1) of the rearranged aryl–Rh species in the absence of o‐ or m‐substituents, ensuring multiple carborhodations take place. However, for 2,5‐dimethylphenyl, which was used as a model substrate, the barrier for carborhodation is increased to 19.4 kcal mol?1, explaining the observed termination of the reaction at 1,2,3,4‐tetra(exo‐norborn‐2‐yl)benzene. Finally, calculations with (Z)‐2‐butene gave a carborhodation barrier of 20.2 kcal mol?1, suggesting that carborhodation of non‐strained, open‐chain substrates would be disfavored relative to protonation. 相似文献
15.
Gold‐Catalyzed CH Annulation of Anthranils with Alkynes: A Facile,Flexible, and Atom‐Economical Synthesis of Unprotected 7‐Acylindoles 下载免费PDF全文
Hongming Jin Long Huang Jin Xie Matthias Rudolph Frank Rominger A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2016,55(2):794-797
The gold‐catalyzed C? H annulation of anthranil derivatives with alkynes offers a facile, flexible, and atom‐economical one‐step route to unprotected 7‐acylindoles. An intermediate α‐imino gold carbene, generated by an intermolecular reaction, promotes ortho‐aryl C? H functionalization to afford the target products. The transformation proceeds with a broad range of substrates under mild conditions. Moreover, the obtained functionalized indole products represent a versatile platform for the construction of diverse indolyl frameworks. 相似文献
16.
Synthesis of Axially Chiral Biaryls through Sulfoxide‐Directed Asymmetric Mild CH Activation and Dynamic Kinetic Resolution 下载免费PDF全文
Dr. Chinmoy Kumar Hazra Quentin Dherbassy Dr. Joanna Wencel‐Delord Prof. Françoise Colobert 《Angewandte Chemie (International ed. in English)》2014,53(50):13871-13875
A mild and robust direct C? H functionalization strategy has been applied to the synthesis of axially chiral biaryls. Such an efficient and stereoselective transformation occurs through an original dynamic kinetic resolution pathway enabling the conversion of diastereomeric mixtures of non‐prefunctionalized substrates into atropisomerically pure, highly substituted biaryl scaffolds. The main feature of this transformation is the use of an enantiopure sulfoxide as both chiral auxiliary and traceless directing group. The potential of newly synthesized biaryls as valuable building blocks is further illustrated. 相似文献
17.
Dr. Akihiro Takada Hiroaki Fujiwara Dr. Kenji Sugimoto Dr. Hirofumi Ueda Prof. Dr. Hidetoshi Tokuyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16400-16403
The total synthesis of (?)‐isoschizogamine was accomplished, featuring the construction of the quaternary carbon center by the modified Johnson–Claisen rearrangement in basic media and the facile assembly of the key tetracyclic quinolone intermediate through a cascade cyclization. The characteristic cyclic aminal was constructed by late‐stage C?H functionalization at the position adjacent to the lactam nitrogen using a combination of CrO3 and nBu4NIO4 and subsequent Bi(OTf)3‐mediated cyclization. 相似文献
18.
Wenzhong Huang Lingli Nang Xiangguang Li Lin Yuan Yinhai Ma Deqiang Liang 《中国化学》2015,33(10):1167-1172
Under the catalysis of only 3 mol% of Br2 at room temperature, indoles reacted rapidly with isatins to form biologically important 3,3‐bis(indole‐3‐yl)indoline‐2‐(1H)‐ones with high efficiency and wide substrate scope. Moreover, we demonstrated that p‐toluenesulfonic acid (TsOH) could serve as a surrogate to catalyze this transformation. 相似文献
19.
Prof. Dr. K. C. Nicolaou Dr. Philipp Heretsch Dr. Abdelatif ElMarrouni Christopher R. H. Hale Dr. Kiran K. Pulukuri Dr. Avinash K. Kudva Dr. Vivek Narayan Prof. Dr. K. Sandeep Prabhu 《Angewandte Chemie (International ed. in English)》2014,53(39):10443-10447
A catalytic asymmetric total synthesis of the potent and selective antileukemic Δ12‐prostaglandin J3 (Δ12‐PGJ3) is described. The convergent synthesis proceeded through intermediates 2 and 3 , formed enantioselectively from readily available starting materials and coupled through an aldol reaction followed by dehydration to afford stereoselectively the cyclopentenone alkylidene structural motif of the molecule. 相似文献
20.
Palladium‐Catalyzed Construction of Heteroatom‐Containing π‐Conjugated Systems by Intramolecular Oxidative CH/CH Coupling Reaction 下载免费PDF全文
Kenta Saito Dr. Prasanna Kumara Chikkade Prof. Dr. Motomu Kanai Prof. Dr. Yoichiro Kuninobu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8365-8368
Synthesis of heteroatom‐containing ladder‐type π‐conjugated molecules was successfully achieved via a palladium‐catalyzed intramolecular oxidative C?H/C?H cross‐coupling reaction. This reaction provides a variety of π‐conjugated molecules bearing heteroatoms, such as nitrogen, oxygen, phosphorus, and sulfur atoms, and a carbonyl group. The π‐conjugated molecules were synthesized efficiently, even in gram scale, and larger π‐conjugated molecules were also obtained by a double C?H/C?H cross‐coupling reaction and successive oxidative cycloaromatization. 相似文献