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Enantioselective Pd‐Catalyzed Allylic Alkylation Reactions of Dihydropyrido[1,2‐a]indolone Substrates: Efficient Syntheses of (−)‐Goniomitine, (+)‐Aspidospermidine,and (−)‐Quebrachamine 下载免费PDF全文
Beau P. Pritchett Jun Kikuchi Dr. Yoshitaka Numajiri Prof. Dr. Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2016,55(43):13529-13532
The successful application of dihydropyrido[1,2‐a]indolone (DHPI) substrates in Pd‐catalyzed asymmetric allylic alkylation chemistry facilitates rapid access to multiple alkaloid frameworks in an enantioselective fashion. Strategic bromination at the indole C3 position greatly improved the allylic alkylation chemistry and enabled a highly efficient Negishi cross‐coupling downstream. The first catalytic enantioselective total synthesis of (?)‐goniomitine, along with divergent formal syntheses of (+)‐aspidospermidine and (?)‐quebrachamine, are reported herein. 相似文献
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Immobilized Catalysts for Iridium‐Catalyzed Allylic Amination: Rate Enhancement by Immobilization 下载免费PDF全文
Dr. Chandi C. Malakar Prof. Dr. Günter Helmchen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7127-7134
The first immobilized catalyst for Ir‐catalyzed asymmetric allylic aminations is described. The catalyst is a cationic (π‐allyl)Ir complex bound by cation exchange to an anionic silica gel support. Preparation of the catalyst is facile, and the supported catalyst displayed considerably enhanced activity compared with the parent homogeneous catalyst. Up to 43 consecutive amination runs were possible in recycling experiments. 相似文献
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Pentacoordinated Carboxylate π‐Allyl Nickel Complexes as Key Intermediates for the Ni‐Catalyzed Direct Amination of Allylic Alcohols 下载免费PDF全文
Dr. Yusuke Kita Hironobu Sakaguchi Dr. Yoichi Hoshimoto Daisuke Nakauchi Dr. Yasuhito Nakahara Prof. Dr. Jean‐François Carpentier Prof. Dr. Sensuke Ogoshi Prof. Dr. Kazushi Mashima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14571-14578
Direct amination of allylic alcohols with primary and secondary amines catalyzed by a system made of [Ni(1,5‐cyclooctadiene)2] and 1,1′‐bis(diphenylphosphino)ferrocene was effectively enhanced by adding nBu4NOAc and molecular sieves, affording the corresponding allyl amines in high yield with high monoallylation selectivity for primary amines and high regioselectivity for monosubstituted allylic alcohols. Such remarkable additive effects of nBu4NOAc were elucidated by isolating and characterizing some nickel complexes, manifesting the key role of a charge neutral pentacoordinated η3‐allyl acetate complex in the present system, in contrast to usual cationic tetracoordinated complexes earlier reported in allylic substitution reactions. 相似文献
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Paul M. Wehn Dr. J. Du Bois Prof. 《Angewandte Chemie (International ed. in English)》2009,48(21):3802-3805
Weaving an intricate web : A stereoselective synthesis of (?)‐agelastatin A has been developed, which requires 11 steps from commercially available starting material. The application of a Rh‐catalyzed intramolecular olefin aziridination reaction and the subsequent manipulation of the resulting tricyclic intermediate (see scheme) punctuate this study.
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Gold(I) as an Artificial Cyclase: Short Stereodivergent Syntheses of (−)‐Epiglobulol and (−)‐4β,7α‐ and (−)‐4α,7α‐Aromadendranediols 下载免费PDF全文
Dr. Javier Carreras Madeleine Livendahl Dr. Paul R. McGonigal Prof. Antonio M. Echavarren 《Angewandte Chemie (International ed. in English)》2014,53(19):4896-4899
Three natural aromadendrane sesquiterpenes, (?)‐epiglobulol, (?)‐4β,7α‐aromadendranediol, and (?)‐4α,7α‐aromadendranediol, have been synthesized in only seven steps in 12, 15, and 17 % overall yields, respectively, from (E,E)‐farnesol by a stereodivergent gold(I)‐catalyzed cascade reaction which forms the tricyclic aromadendrane core in a single step. These are the shortest total syntheses of these natural compounds. 相似文献
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Christian Gnamm Dipl.‐Chem. Caroline M. Krauter Kerstin Brödner Günter Helmchen Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(9):2050-2054
Pressing the configurational switch : Use of enantiomeric Ir catalysts allows the vinylpiperidine building blocks 2 a and 2 b to be synthesized with high selectivity. Total syntheses of the dendrobate alkaloid (+)‐241 D, its C6‐epimer, and a spruce alkaloid are presented as applications.
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Gold‐Catalyzed Heterogeneous Aerobic Dehydrogenative Amination of α,β‐Unsaturated Aldehydes to Enaminals 下载免费PDF全文
Xiongjie Jin Dr. Kazuya Yamaguchi Prof. Dr. Noritaka Mizuno 《Angewandte Chemie (International ed. in English)》2014,53(2):455-458
Although enaminals (β‐enaminals) are very important compounds and have been utilized as useful synthons for various important compounds, they have been synthesized through non‐green and/or limited procedures until now. Herein, we have successfully developed a green synthetic procedure using a heterogeneous catalyst. In the presence of gold nanoparticles supported on manganese‐oxide‐based octahedral molecular sieves OMS‐2 (Au/OMS‐2), dehydrogenative amination of α,β‐unsaturated aldehydes with amines proceeded efficiently, with the corresponding enaminals isolated in moderate to high yields (50–97 %). The catalysis was truly heterogeneous, and Au/OMS‐2 could be reused. Furthermore, the formal Wacker‐type oxidation of α,β‐unsaturated aldehydes to enaminones has been realized. 相似文献
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Rhodium‐Catalyzed Sequential Allylic Amination and Olefin Hydroacylation Reactions: Enantioselective Synthesis of Seven‐Membered Nitrogen Heterocycles 下载免费PDF全文
Jeffrey S. Arnold Edward T. Mwenda Prof. Dr. Hien M. Nguyen 《Angewandte Chemie (International ed. in English)》2014,53(14):3688-3692
Dynamic kinetic asymmetric amination of branched allylic acetimidates has been applied to the synthesis of 2‐alkyl‐dihydrobenzoazepin‐5‐ones. These seven‐membered‐ring aza ketones are prepared in good yield with high enantiomeric excess by rhodium‐catalyzed allylic substitution with 2‐amino aryl aldehydes followed by intramolecular olefin hydroacylation of the resulting alkenals. This two‐step procedure is amenable to varied functionality and proves useful for the enantioselective preparation of these ring systems. 相似文献
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Phase‐Transfer‐Catalyzed Asymmetric SNAr Reaction of α‐Amino Acid Derivatives with Arene Chromium Complexes 下载免费PDF全文
Prof. Dr. Seiji Shirakawa Kenichiro Yamamoto Prof. Dr. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2015,54(3):838-840
Although phase‐transfer‐catalyzed asymmetric SNAr reactions provide unique contribution to the catalytic asymmetric α‐arylations of carbonyl compounds to produce biologically active α‐aryl carbonyl compounds, the electrophiles were limited to arenes bearing strong electron‐withdrawing groups, such as a nitro group. To overcome this limitation, we examined the asymmetric SNAr reactions of α‐amino acid derivatives with arene chromium complexes derived from fluoroarenes, including those containing electron‐donating substituents. The arylation was efficiently promoted by binaphthyl‐modified chiral phase‐transfer catalysts to give the corresponding α,α‐disubstituted α‐amino acids containing various aromatic substituents with high enantioselectivities. 相似文献
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Direct Asymmetric Dearomatization of Pyridines and Pyrazines by Iridium‐Catalyzed Allylic Amination Reactions 下载免费PDF全文
Ze‐Peng Yang Dr. Qing‐Feng Wu Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2014,53(27):6986-6989
The first iridium‐catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines and pyrazines has been realized. 2,3‐Dihydroindolizine and 6,7‐dihydropyrrolo[1,2‐a]pyrazine derivatives were obtained with excellent yields and enantioselectivity. This methodology features dearomatization by direct N‐allylic alkylation of pyridines or pyrazines under mild reaction conditions. 相似文献