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1.
A Novel Pd‐Catalysed Annulation Reaction for the Syntheses of Pyrroloindoles and Pyrroloquinolines 下载免费PDF全文
Dr. Dattatraya H. Dethe Raghavender Boda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):106-110
Pd‐catalysed annulation reactions between indole derivatives and internal alkyne esters leading to various pyrrolo[1,2‐a]indoles and pyrroloquinolines have been developed. The strategy involves an intermolecular addition of the indole nitrogen on to the internal alkyne ester followed by an intramolecular insertion of a vinyl–palladium complex into the carbonyl group. This method offers a facile and practical approach to pyrrolo[1,2‐a]indoles and pyrroloquinolines. 相似文献
2.
[reaction: see text] Reaction of an enoate bearing an epoxysilane moiety at the alpha-position with lithium enolate of 2-chloroacetamide afforded highly functionalized cyclopropane derivatives via a tandem process that involves Michael addition, ring opening of the epoxide, Brook rearrangement, and intramolecular alkylation. 相似文献
3.
Stereoselective Synthesis of 1,2,3‐Triazolooxazine and Fused 1,2,3‐Triazolo‐δ‐Lactone Derivatives 下载免费PDF全文
The stereoselective synthesis of 1,2,3‐triazolooxazine and fused 1,2,3‐triazolo‐δ‐lactone by applying chemoenzymatic methods is described. trans‐2‐Azidocyclohexanol was successfully resolved by Novozyme 435 with an ee value of 99%. Installation of the alkyne moiety on the enantiomerically enriched azidoalcohol by O‐alkylation, followed by intramolecular azide? alkyne [3+2] cycloaddition resulted in the desired 1,2,3‐triazolooxazine derivative. Enantiomerically pure azidocyclohexanol was also subjected to the Huisgen 1,3‐dipolar cycloaddition reaction with dimethylacetylene dicarboxylate, followed by intramolecular cyclization of the corresponding cycloadduct, to furnish a fused 1,2,3‐triazolo‐δ‐lactone. 相似文献
4.
New star‐shaped phosphorus‐containing flame retardants were synthesized by phospha‐Michael‐addition of diphenylphosphine oxide and dimethyl phosphite to oligofunctional acrylates. The products were examined via UL 94 V‐rating and thermogravimetric analysis in three different epoxy resin systems compared to the recently described correspondent derivatives based on the phosphinate‐type 6‐oxido‐6H‐dibenzo[c,e][1,2]oxaphosphinine. The influence of a systematically altered chemical environment of the phosphorus atom on the flame retardancy and the char yield was investigated. Furthermore, the glass transition temperatures of the modified resins were studied via differential scanning calorimetry, including the deviation after an additional treatment at elevated temperature. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
5.
Prof. Takahide Fukuyama Yuko Ohta Dr. Célia Brancour Kazusa Miyagawa Prof. Ilhyong Ryu Dr. Anne‐Lise Dhimane Prof. Louis Fensterbank Prof. Max Malacria 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(23):7243-7247
We have developed novel Rh‐catalyzed [n+1]‐type cycloadditions of 1,4‐enyne esters, which involve an acyloxy migration as a key step. The efficient preparation of functionalized resorcinols, including biaryl derivatives, from readily available 1,4‐enyne esters and CO was achieved by Rh‐catalyzed [5+1] cycloaddition accompanied by 1,2‐acyloxy migration. When enyne esters had an internal alkyne moiety, the reaction proceeded by a [4+1]‐type cycloaddition involving 1,3‐acyloxy migration, leading to cyclopentenones. 相似文献
6.
Mechanistic Understanding of the Divergent Cyclizations of o‐Alkynylbenzaldehyde Acetals and Thioacetals Catalyzed by Metal Halides 下载免费PDF全文
Yanhua Mi Tao Zhou Kung‐Pern Wang Prof. Daesung Lee Prof. Yuanzhi Xia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17256-17268
The mechanisms of regiodivergent cyclizations of o‐alkynylbenzaldehyde acetals and thioacetals catalyzed by Pd and Pt halides are studied. DFT calculations found that both reactions are initiated by electrophilic activation of the acetylenic moiety instead of the previously proposed metal‐triggered C?X (X=O, S) cleavage. Both the regioselective cyclization of the π‐alkyne complex and the chemoselective [1,2]‐migration in the carbenoid intermediate were determined as key steps to achieving the observed divergence. For acetal derivatives containing an internal alkyne, the 6‐endo‐dig cyclization is more favorable and leads to the carbenoid intermediate easily through further steps of C?X fragmentation and carbocation cyclization. Then, from the carbenoid intermediate, the [1,2]‐migration of sulfur is easier than that of H, Me, and Ph; whereas, a reversed aptitude was predicted for the oxygen analogue, which is consistent with the greater ability of sulfur atoms to stabilize β‐carbocations. However, for precursors containing a terminal alkyne, the 5‐exo‐dig pathway is preferred and only the 1,2‐disubstituted indene product is seen, irrespective of the nature of the acetal; thus, a different product from that reported in the literature is predicted for benzaldehyde acetal with a terminal alkyne at the ortho position. This prediction led us to reconsider some of the reported results and hidden realities were uncovered with solid new experimental evidence. 相似文献
7.
In the presence of N, N′‐dicyclohexylcarbodiimide, 2‐aminopyridine and its derivatives (2) condensed with 2, 2‐di‐hydropolyfluoroalkanoic adds (1) to give the corresponding amides. Subsequent intramolecular Micheal addition‐elimination reactions of the fluorine‐containing amides under basic conditions gave 4‐fluoroalkyl‐2H‐pyrido[1,2‐a]pyrimidin‐2‐ones (3) in good yields. 相似文献
8.
Vladimír Bariak Dr. Andrea Malastová Dr. Ambroz Almássy Prof. Radovan Šebesta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13445-13453
An intramolecular Li–Si exchange was observed on various lithiated ferrocenylbenzyl silyl ethers. The thermodynamically more stable C‐silylated isomers were isolated in good yields and fully characterized. The reaction mechanism of the [1,4] retro‐Brook rearrangement was investigated by DFT calculations. Two distinct reaction routes were proposed and a possible stabilization effect of the ferrocenyl fragment on the C‐silylated isomers was described. The diastereoselective rearrangement of the trimethylsilyl group to the ortho position of the ferrocenyl cyclopentadienyl ring was also accomplished and the absolute configuration of the product was determined. 相似文献
9.
M. Josalves M. Alice Carvalho M. Fernanda J. R. P. Proena Brian L. Booth 《Journal of heterocyclic chemistry》2000,37(5):1041-1048
The reaction of ethyl(Z)‐N‐(2‐amino‐1,2‐dicyanovinyl)formimidate 6 with carbonyl compounds in the presence of triethyl amine occurs with formation of the Schiff s base and intramolecular hydrolysis of the adjacent cyano group to give the alkylideneamino derivatives 8a‐f . When the α‐carbon of the ketone has at least one proton, the prolonged contact of 8a‐f with triethylamine causes intramolecular cyclization between this carbon and the imidate carbon atom to form a seven membered ring. This is followed by cyclization of the cyano and amido groups, leading to the pyrrolo[4,3‐b][1,4]diazepines 9 . If a strong base is used the first ring to be formed is the pyrrole ring as evidenced in the reaction of 8a with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene leading to 14 . The subsequent addition of methyl amine to the reaction mixture, caused cleavage of the alkylideneamino unit and formation of the amidine function from the imi date ( 15 ). The addition of acid to the imidates 8a and 8f led to the diazepine compounds 10a and 10f respectively. A suspension of compound 8e in ethanol and triethylamine evolved to a pyrazinone structure 12 under kinetic conditions (4 hours, room temperature) and to the pyrrolo[4,3‐b][1,4]diazepine 9e under thermodynamic conditions (48 hours, room temperature). 相似文献
10.
Pablo Morán‐Poladura Dr. Eduardo Rubio Prof. Dr. José M. González 《Angewandte Chemie (International ed. in English)》2015,54(10):3052-3055
The cycloisomerization reaction of 1‐(iodoethynyl)‐2‐(1‐methoxyalkyl)arenes and related 2‐alkyl‐substituted derivatives gives the corresponding 3‐iodo‐1‐substituted‐1H‐indene under the catalytic influence of IPrAuNTf2 [IPr=1,3‐bis(2,6‐diisopropyl)phenylimidazol‐2‐ylidene; NTf2=bis(trifluoromethanesulfonyl)imidate]. The reaction takes place in 1,2‐dichloroethane at 80 °C, and the addition of ttbp (2,4,6‐tri‐tert‐butylpyrimidine) is beneficial to accomplish this new transformation in high yield. The overall reaction implies initial assembly of an intermediate gold vinylidene upon alkyne activation by gold(I) and a 1,2‐iodine‐shift. Deuterium labeling and crossover experiments, the magnitude of the recorded kinetic primary isotopic effect, and the results obtained from the reaction of selected stereochemical probes strongly provide support for concerted insertion of the benzylic C? H bond into gold vinylidene as the step responsible for the formation of the new carbon–carbon bond. 相似文献
11.
《Journal of heterocyclic chemistry》2017,54(2):1193-1198
A facile and convenient synthesis of an interesting N‐(1H‐pyrazol‐5‐yl)‐hexahydroquinoline‐3‐carbonitrile and octahydropyrazolo[4′,3′:5,6]pyrimido[1,2‐a ]quinoline‐6‐carbonitrile derivatives via the versatile readily accessible cyclic enaminones incorporating pyrazole moiety was accomplished. 相似文献
12.
The development of efficient methods for stereocontrolled synthesis of polyol derivatives has been of continuing interest for the synthetic community. We describe herein tandem olefin cross‐metathesis/hemiacetalization/intramolecular oxa‐Michael addition of allylic/homoallylic alcohols, α,β‐unsaturated ketones, and aldehydes, which enabled the synthesis of syn‐1,2‐ and syn‐1,3‐diol derivatives in a step‐economical manner. A series of differentially protected polyol derivatives could be obtained in subsequent transformations via chemoselective/regioselective cleavage of the acetal moiety of the tandem reaction products. 相似文献
13.
FeCl3‐Mediated Three‐Component Cascade Reaction: An Effective Approach to the Construction of Highly Functionalized Pyrrolo[1,2‐c]quinazolinones 下载免费PDF全文
Hu‐Fei Zheng Dr. Zhi‐Hua Yu Wei Yuan Prof. Dr. Zi‐Long Tang John Clough Yu‐Cheng Gu Prof. Dr. De‐Qing Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1711-1719
An unexpected FeCl3‐mediated three‐component cascade reaction has been used to construct structurally diverse pyrrolo[1,2‐c]quinazolinone derivatives with potential biological activities. This method has advantages of mild conditions, simple work‐up, as well as wide substrate scope, which makes it a powerful approach to the synthesis of diverse pyrrolo[1,2‐c]quinazolinones. This cascade reaction involves 1,3‐dipolar cycloaddition between azomethine ylides and allenoates, followed by intramolecular nucleophilic addition in the presence of FeCl3. The obtained products could be easily transformed into derivatives with the pyrrolo[2,3‐c]quinazoline alkaloid skeleton. 相似文献
14.
Reaction of 3,5‐diaminothiophene‐2‐carbonitrile derivatives 3a‐c with ethoxycarbonylmethyl isothiocyanate and/or N‐[bis(methylthio)methylene]glycine ethyl ester led to formation of 7‐substituted‐8‐amino‐5‐thioxo‐6H‐imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one derivatives 6a‐c and 7‐substituted‐8‐amino‐5‐(methylthio)imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one 7a‐c , respectively. Also, the synthetic potential of the β‐enaminonitrile moiety in 3a‐c has been explored; it proved to be a promising candiate for the synthesis of 1,6‐disubstituted‐2,4‐diamino‐7,8‐dihydro‐8‐oxopyrrolo[1,2‐a]thieno[2,3‐e]pyrimidine derivatives 10a‐f and pyrido[2′,3′:6,5]pyrimido[3,4‐a]benzimidazole derivatives 12a,b . 相似文献
15.
Chelation‐Assisted Nickel‐Catalyzed Oxidative Annulation via Double C−H Activation/Alkyne Insertion Reaction 下载免费PDF全文
Dr. Luis C. Misal Castro Atsushi Obata Yoshinori Aihara Prof. Naoto Chatani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1362-1367
A nickel/NHC system for regioselective oxidative annulation by double C?H bond activation and concomitant alkyne insertion is described. The catalytic reaction requires a bidentate directing group, such as an 8‐aminoquinoline, embedded in the substrate. Various 5,6,7,8‐tetrasubstituted‐N‐(quinolin‐8‐yl)‐1‐naphthamides can be prepared as well as phenanthrene and benzo[h]quinoline amide derivatives. Diarylalkynes, dialkylalkynes, and arylalkylalkynes can be used in the system. A Ni0/NiII catalytic cycle is proposed as the main catalytic cycle. The alkyne plays a double role as a two‐component coupling partner and as a hydrogen acceptor. 相似文献
16.
Tatyana A. Stroganova Vladimir K. Vasilin Polina S. Shestakova Viktor M. Red'kin Gennady D. Krapivin 《Journal of heterocyclic chemistry》2015,52(1):227-234
3‐Acylaminofuro[2,3‐b]pyridine derivatives have been synthesized, and their behavior under acidic and basic conditions was studied. A new base‐catalyzed rearrangement of 3‐acylaminofuro[2,3‐b]pyridine derivatives into 3‐(oxazol‐4‐yl)pyridine‐2‐ones has been founded. 相似文献
17.
Rhodium‐Catalyzed Intramolecular [5+2] Cycloaddition of Inverted 3‐Acyloxy‐1,4‐enyne and Alkyne: Experimental and Theoretical Studies 下载免费PDF全文
Dr. Xiaoxun Li Wangze Song Xiaona Ke Prof. Dr. Xiufang Xu Prof. Dr. Peng Liu Prof. Dr. K. N. Houk Dr. Xian‐liang Zhao Prof. Dr. Weiping Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7079-7083
By switching the position of the alkene and alkyne, a new type of 3‐acyloxy‐1,4‐enyne (ACE) five‐carbon building block was developed for Rh‐catalyzed intramolecular [5+2] cycloaddition. An electron‐withdrawing acyl group on the alkyne termini of the ACE was essential for a regioselective 1,2‐acyloxy migration. This new method provided bicyclic [5.3.0]decatrienes that are different from previous methods because of the positions of the alkenes and the acyloxy group. Multiple mechanistic pathways become possible for this new [5+2] cycloaddition and they are investigated by computational studies. 相似文献
18.
Pablo Morn‐Poladura Eduardo Rubio Jos M. Gonzlez 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(10):3095-3098
The cycloisomerization reaction of 1‐(iodoethynyl)‐2‐(1‐methoxyalkyl)arenes and related 2‐alkyl‐substituted derivatives gives the corresponding 3‐iodo‐1‐substituted‐1H‐indene under the catalytic influence of IPrAuNTf2 [IPr=1,3‐bis(2,6‐diisopropyl)phenylimidazol‐2‐ylidene; NTf2=bis(trifluoromethanesulfonyl)imidate]. The reaction takes place in 1,2‐dichloroethane at 80 °C, and the addition of ttbp (2,4,6‐tri‐tert‐butylpyrimidine) is beneficial to accomplish this new transformation in high yield. The overall reaction implies initial assembly of an intermediate gold vinylidene upon alkyne activation by gold(I) and a 1,2‐iodine‐shift. Deuterium labeling and crossover experiments, the magnitude of the recorded kinetic primary isotopic effect, and the results obtained from the reaction of selected stereochemical probes strongly provide support for concerted insertion of the benzylic C H bond into gold vinylidene as the step responsible for the formation of the new carbon–carbon bond. 相似文献
19.
Antonio Da Settimo Giampaolo Primofiore Federico Da Settimo Gianluca Pardi Francesca Simorini Anna Maria Marini 《Journal of heterocyclic chemistry》2002,39(5):1007-1011
The synthetic potential of the title compounds benzimidazo[1,2‐a]quinazoline‐5(7H)‐one 2a and 5,7‐dihydro‐5‐oxopyrido[3′,2′:5,6]pyrimido[1,2‐a]benzimidazole 2b for the construction of novel polyhetero‐cyclic frameworks is reported. Compounds 2a,b , by conversion into their thio analogues 3a,b , were used for the synthesis of tetrazole ( 5a,b ) and triazole ( 7a,b ) derivatives, as well as for an unexpected synthesis of tri‐azoles 8a,b , isomers of 7a,b , resulting from the occurrence of a Dimroth rearrangement. 相似文献
20.
Generation and Rearrangement of N,O‐Dialkenylhydroxylamines for the Synthesis of 2‐Aminotetrahydrofurans 下载免费PDF全文
Jongwoo Son Tyler W. Reidl Ki Hwan Kim Dr. Donald J. Wink Prof. Laura L. Anderson 《Angewandte Chemie (International ed. in English)》2018,57(22):6597-6600
A new diastereoselective route to 2‐aminotetrahydrofurans has been developed from N,O‐dialkenylhydroxylamines. These intermediates undergo a spontaneous C?C bond‐forming [3,3]‐sigmatropic rearrangement followed by a C?O bond‐forming cyclization. A copper‐catalyzed N‐alkenylation of an N‐Boc‐hydroxylamine with alkenyl iodides, and a base‐promoted addition of the resulting N‐hydroxyenamines to an electron‐deficient allene, provide modular access to these novel rearrangement precursors. The scope of this de novo synthesis of simple nucleoside analogues has been explored to reveal trends in diastereoselectivity and reactivity. In addition, a base‐promoted ring‐opening and Mannich reaction has been discovered to covert 2‐aminotetrahydrofurans to cyclopentyl β‐aminoacid derivatives or cyclopentenones. 相似文献