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Roberto Fernández de la Pradilla Alejandro Castellanos Mercedes Ureña Alma Viso 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1461-1462
Hydroxy sulfinyl dienes yielded functionalized tetrahydrofurans through nucleophilic and metal-catalyzed epoxidations.[1] Effective oxirane cleavage has been achieved in these systems and a formal synthesis of (?)-Kumausallene is reported. 相似文献
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Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene OH Insertion Reaction 下载免费PDF全文
Simon M. Nicolle Dr. William Lewis Prof. Dr. Christopher J. Hayes Prof. Dr. Christopher J. Moody 《Angewandte Chemie (International ed. in English)》2015,54(29):8485-8489
Copper‐ or rhodium‐catalyzed reactions of diazocarbonyl compounds with β‐hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single‐step process starts as a carbene O? H insertion reaction, but is diverted by an intramolecular aldol reaction. 相似文献
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The regioselective ring opening of epoxy alcohols is an effective method for the synthesis of different types of oxacycles. The 5-exo opening being preferred vs. the 6-endo mode, according to Baldwin rules, the use of silyl-substituted oxiranes has been reported as a possible method to favor the 6-endo cyclization. However, there is a need for a detailed study on the different factors (structural factors, catalyst nature or conditions) that influence this process. In this paper, the acid-catalyzed cyclization of epoxysilyl alcohols was studied, focusing on the effect of substituents and reaction conditions on the outcome of the process. Two types of heterocycles (tetrahydrofurans or tetrahydropyrans) were selectively obtained depending on the structure of the initial epoxysilyl alcohol. Interestingly, cyclization of hindered epoxysilyl alcohols mainly proceeds through an unexpected side reaction, which implies a previous isomerization to an aldehyde. A mechanistic proposal for the formation of the different products is presented. 相似文献
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Siliang Ming Dr. Saira Qurban Prof. Dr. Yu Du Prof. Dr. Weiping Su 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(50):12742-12746
Unlike the comprehensive development of tandem multi-metallic catalysis, bimetallic synergistic catalysis has been challenging to achieve high stereoselectivity with the generation of multi-stereogenic centers. Herein, an efficient synergistic catalysis for the diastereo- and enantioselective synthesis of multi-substituted tetrahydrofuran derivatives has been developed. Under mild reaction conditions, a series of target molecules with three consecutive stereocenters were synthesized by a palladium(0)/rhodium(III) bimetal-catalyzed asymmetric decarboxylative [3+2]-cycloaddition of vinylethylene carbonates with α,β-unsaturated carbonyl compounds. The corresponding adducts were obtained with moderate to high yields (67 %∼98 %) and excellent stereoselectivities (>20 : 1 d.r., up to 99 % ee). 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(24):6862-6865
The development of a direct and highly stereoselective synthesis of 2,3,5‐substituted tetrahydrofurans has been accomplished through a combination of batch‐ and microchip‐MS‐experiments. This sequential transformation comprises a Lewis acid‐mediated reaction of bis(silyl) dienediolate 1 and a broad range of aldehydes, furnishing products with three new σ‐bonds and three stereogenic centers in a one‐pot process with typically good yields and excellent stereoselectivity. Key steps which have been elucidated primarily with microchip‐MS‐experiments include a vinylogous aldol reaction and a Prins‐type cyclization. Furthermore, a titanium BINOL complex is a powerful chiral catalyst for this process. The products were further converted into bi‐ and tricylic products by carbonyl–ene reactions, proceeding with excellent yields and diastereoselectivity. 相似文献
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Selective Synthesis of Cyclooctanoids by Radical Cyclization of Seven‐Membered Lactones: Neutron Diffraction Study of the Stereoselective Deuteration of a Chiral Organosamarium Intermediate 下载免费PDF全文
Dr. Xavier Just‐Baringo Jemma Clark Dr. Matthias J. Gutmann Prof. Dr. David J. Procter 《Angewandte Chemie (International ed. in English)》2016,55(40):12499-12502
Seven‐membered lactones undergo selective SmI2–H2O‐promoted radical cyclization to form substituted cyclooctanols. The products arise from an exo‐mode of cyclization rather than the usual endo‐attack employed in the few radical syntheses of cyclooctanes. The process is terminated by the quenching of a chiral benzylic samarium. A labeling experiment and neutron diffraction study have been used for the first time to probe the configuration and highly diastereoselective deuteration of a chiral organosamarium intermediate. 相似文献
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Mesram Manoj Kumar Dr. Parikibanda Venkataramana Prof. Parikibanda Yadagiri Swamy Dr. Yadaiah Chityala 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17713-17721
A new route to synthesis of various mono-N-substituted hydrazines and hydrazides by involving in a new C−N bond formation by using N-amino-1,8-naphthalimide as a regenerated precursor was invented. Aniline and phenylhydrazines are reproduced upon reacting these individually with 1,8-naphthalic anhydride followed by hydrazinolysis. The practicality and simplicity of this C−N dihalo alkanes; developed a synthon for bond formation protocol was exemplified to various hydrazines and hydrazides. N-amino-1,8-naphthalimide is suitable synthon for transformation for selective formation of mono-substituted hydrazine and hydrazide derivatives. Those are selective mono - amidation of hydrazine with acid halides; mono-N-substituted hydrazones from aldehydes; synthesis of N-aminoazacycloalkanes from acetohydrazide scaffold and inserted to hydroxy derivatives; distinct synthesis of N,N-dibenzylhydrazines and N-benzylhydrazines from benzyl halides; synthesis of N-amino-amino acids from α-halo esters. Ecofriendly reagent N-amino-1,8-naphthalimide was regenerated with good yields by the hydrazinolysis in all procedures. 相似文献
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Lubin Xu 《Tetrahedron letters》2008,49(3):500-503
Ti(III)-mediated intramolecular free radical cyclization of epoxyallene ethers in an exo-mode was studied. The reaction afforded an efficient and highly regioselective method of synthetically important 3-vinyl-4-hydroxymethyl tetrahydrofurans. 相似文献
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Yong-Kai Xi Prof. Dr. Hongbin Zhang Rui-Xi Li Shi-Yuan Kang Jin Li Yan Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):3005-3009
Cyclodipeptide 2,5-diketopiperazines (DKP) are privileged structural units present in drugs and natural alkaloids. This work reports a new method for the synthesis of biologically important DKP scaffolds based on an intramolecular nucleophilic α-addition of general amides towards an alkynamide system. The utility of this umpolung cyclization mediated by trimethyl phosphine and l -glutamic acid is highlighted by its application to the concise total syntheses of 6-methoxyspirotryprostatin B (the first total synthesis), spirotryprostatin A, and spirotryprostatin B. 相似文献
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Biomimetic Total Synthesis of Cyanosporaside Aglycons from a Single Enediyne Precursor through Site‐Selective p‐Benzyne Hydrochlorination 下载免费PDF全文
Kei Yamada Prof. Dr. Martin J. Lear Takaya Yamaguchi Dr. Shuji Yamashita Prof. Dr. Ilya D. Gridnev Prof. Dr. Yujiro Hayashi Prof. Dr. Masahiro Hirama 《Angewandte Chemie (International ed. in English)》2014,53(50):13902-13906
The cyanosporasides A–F are a collection of monochlorinated benzenoid derivatives isolated from the marine actinomycetes Salinispora and Streptomyces sp. All derivatives feature one of two types of cyanocyclopenta[a]indene frameworks, which are regioisomeric in the position of a single chlorine atom. It is proposed that these chloro‐substituted benzenoids are formed biosynthetically through the cycloaromatization of a bicyclic nine‐membered enediyne precursor. Herein, we report the synthesis of such a bicyclic precursor, its spontaneous transannulation into a p‐benzyne, and its differential 1,4 hydrochlorination reactivity under either organochlorine or chloride‐salt conditions. Our bioinspired approach culminated in the first regiodivergent total synthesis of the aglycons A/F and B/C, as well as cyanosporasides D and E. In addition, empirical insights into the site selectivity of a natural‐like p‐benzyne, calculated to be a ground‐state triplet diradical, to hydrogen, chlorine, and chloride sources are revealed. 相似文献
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Cascade Biocatalysis for Sustainable Asymmetric Synthesis: From Biobased l‐Phenylalanine to High‐Value Chiral Chemicals 下载免费PDF全文
Dr. Yi Zhou Dr. Shuke Wu Prof. Dr. Zhi Li 《Angewandte Chemie (International ed. in English)》2016,55(38):11647-11650
Sustainable synthesis of useful and valuable chiral fine chemicals from renewable feedstocks is highly desirable but remains challenging. Reported herein is a designed and engineered set of unique non‐natural biocatalytic cascades to achieve the asymmetric synthesis of chiral epoxide, diols, hydroxy acid, and amino acid in high yield and with excellent ee values from the easily available biobased l ‐phenylalanine. Each of the cascades was efficiently performed in one pot by using the cells of a single recombinant strain over‐expressing 4–10 different enzymes. The cascade biocatalysis approach is promising for upgrading biobased bulk chemicals to high‐value chiral chemicals. In addition, combining the non‐natural enzyme cascades with the natural metabolic pathway of the host strain enabled the fermentative production of the chiral fine chemicals from glucose. 相似文献
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Organocatalytic,Enantioselective Synthesis of Cyclohexadienone Containing Hindered Spirocyclic Ethers through an Oxidative Dearomatization/Oxa‐Michael Addition Sequence 下载免费PDF全文
Reddy Rajasekhar Reddy Dr. Satish Sonbarao Gudup Prof. Prasanta Ghorai 《Angewandte Chemie (International ed. in English)》2016,55(48):15115-15119
An unprecedented enantioselective oxa‐Michael reaction of α‐tertiary alcohols using cinchona‐alkaloid‐based chiral bifunctional squaramide catalysts is reported. An oxidative dearomatization of phenol followed by an enantioselective oxa‐Michael addition sequence provided a broad array of chiral sterically hindered tetrahydrofurans and tetrahydropyrans attached to a cyclohexadienone moiety in spiro fashion. In general, good yields and excellent enantioselectivities (up to 99 %) were observed. The chiral oxo‐cycles obtained have easily been transformed into chromans without disturbing the enantioselectivity. 相似文献
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Intramolecular Metalloamination of N,N‐Dimethylhydrazinoalkenes: A Versatile Method to Access Functionalized Piperidines and Pyrrolidines 下载免费PDF全文
Bryce Sunsdahl Adrian R. Smith Prof. Dr. Tom Livinghouse 《Angewandte Chemie (International ed. in English)》2014,53(52):14352-14356
Highly diastereoselective metalloamination/cyclization reactions of zinc(II) hydrazides obtained through reaction of diethylzinc with N,N‐dimethylhydrazinoalkenes are described. The resulting organozinc intermediates undergo facile allylation and acylation, in situ, to provide the corresponding functionalized piperidines and pyrrolidines. 相似文献