- Zinc-Catalyzed Tandem Diels–Alder Reactions of Enynals with Alkenes: Generation and Trapping of Cyclic o-Quinodimethanes (o-QDMs)
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A systematic investigation of ZnCl2-catalyzed reactions of enynals with alkenes has been undertaken. Structurally unique propeller-like products could be obtained under mild conditions. Cyclic o-quinodimethanes (o-QDMs) are generated through [4+2] cycloaddition between enynals and alkenes. Both electron-poor and electron-rich dienophiles could be used to trap the active intermediate through [4+2] cycloaddition. But [1,5]-H shift products could also be observed when electron-rich alkenes were used as dienophile. DFT calculations were performed to understand the reaction mechanism. A competition between the [4+2] cycloaddition and [1,5]-H shift was proposed for the transformation of cyclic o-QDMs. The selectivity could be affected by the properties of the substrates. (Figure presented.).
- Zhang, Jiantao,Xiao, Yelin,Chen, Kai,Wu, Wanqing,Jiang, Huanfeng,Zhu, Shifa
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- Mechanistic insight into transition metal-catalyzed reaction of enynal/enynone with alkenes: Metal-dependent reaction pathway
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A systematic study of the transition metal-catalyzed reaction of enynal/enynone with alkenes has been reported. It was found that the reaction has two metal-dependent reaction pathways. One led to the formation of 1,2-DHN, while another led to cyclic-o-QDM.
- Zhu, Shifa,Huang, Hua,Zhang, Zhicai,Ma, Tongmei,Jiang, Huanfeng
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- Gold Catalysis Meets Materials Science – A New Approach to π-Extended Indolocarbazoles
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Herein we describe a modular, convergent synthesis of substituted benzo[a]benzo[6,7]-indolo[2,3-h]carbazoles (BBICZs) using a bidirectional gold-catalyzed cyclization reaction as a key step. A building block strategy enabled the easy variation of substituents at different positions of the core structure and a general analysis of substitution effects on the materials properties of the target compounds. All BBICZs were fully characterized and their optical and electronic properties were studied experimentally as well as by computational methods. Organic thin-film transistors based on eight selected derivatives were fabricated by vacuum deposition and charge-carrier mobilities up to 1 cm2/Vs were measured. (Figure presented.).
- Hendrich, Christoph M.,Bongartz, Lukas M.,Hoffmann, Marvin T.,Zschieschang, Ute,Borchert, James W.,Sauter, Désirée,Kr?mer, Petra,Rominger, Frank,Mulks, Florian F.,Rudolph, Matthias,Dreuw, Andreas,Klauk, Hagen,Hashmi, A. Stephen K.
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supporting information
p. 549 - 557
(2020/12/07)
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- Catalytic asymmetric three-component reaction of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate
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An efficient enantioselective synthesis of cyclic α-aminophosphonates via multicomponent reactions of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate has been developed with the use of a chiral silver spirocyclic phosphate as the catalyst. This protocol provides straightforward access to a series of chiral C1-phosphonylated 1,2-dihydroisoquinoline derivatives with high yields (up to 99%) and high enantioselectivities (up to 94% ee) for a broad substrate scope. The products could be further transformed into densely functionalized compounds and corresponding α-aminophosphonic acids.
- Zou, Liangliang,Huang, Jiaying,Liao, Na,Liu, Yan,Guo, Qixiang,Peng, Yungui
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supporting information
p. 6932 - 6937
(2020/09/15)
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- Gold-Catalyzed Cyclization of 2-Alkynylaldehyde Cyclic Acetals via Hydride Shift for the Synthesis of Indenone Derivatives
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An efficient gold-catalyzed cyclization of 2-alkynylaldehyde cyclic acetals has been developed for the synthesis of indenone derivatives. A wide variety of functionalized indenone derivatives can be obtained in good-to-excellent yields. HMBC and NOESY NMR analyses and mechanistic elucidation experiments revealed that the cyclization occurs via a 1,5-H shift. The cyclic acetal group promoted the 1,5-H shift by activating the benzylic C-H bond and preventing the migration of the alkoxy group by tethering both alkoxy groups.
- Yamada, Tsuyoshi,Park, Kwihwan,Tachikawa, Takumu,Fujii, Akiko,Rudolph, Matthias,Hashmi, A. Stephen K.,Sajiki, Hironao
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supporting information
p. 1883 - 1888
(2020/03/03)
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- Gold-Catalyzed Cyclisation by 1,4-Dioxidation
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Amide-substituted diynes were cyclized in the presence of a cationic gold catalyst and an external nucleophile leading to 1-indenones and 1-iminoindenones. The electron-donating features of the nitrogen atom enable the formation of a reactive ketene iminium ion, which can be trapped by either diphenyl sulfoxide or anthranil as nucleophiles in a subsequent oxidation step, providing substituted inden-1-on-3-carboxamides.
- Claus, Vanessa,Molinari, Lise,Büllmann, Simon,Thusek, Jean,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 9385 - 9389
(2019/04/30)
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- Gold-Catalyzed Ring Expansion of Enyne-Lactone: Generation and Transformation of 2-Oxoninonium
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An efficient gold-catalyzed ring-expansion reaction of enyne-lactones to form 2-oxoninonium intermediates is reported. The 2-oxoninonium generated in this work could undergo further 6π electrocyclization and aromatization reaction to produce different aromatic compounds.
- Luo, Kui,Cao, Tongxiang,Jiang, Huanfeng,Chen, Lianfen,Zhu, Shifa
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supporting information
p. 5856 - 5859
(2017/11/10)
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- Insights into the Gold-Catalyzed Propargyl Ester Rearrangement/Tandem Cyclization Sequence: Radical versus Gold Catalysis - Myers-Saito- versus Schmittel-Type Cyclization
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A detailed study of the gold-catalyzed tandem 1,3-carboxy migration/allene-enyne cycloisomerization was undertaken. It was found that after the initial allene formation the selectivity of the reaction is strongly influenced by the polarization of the remaining alkyne. Depending on the substitution pattern of the starting diynes, either a Schmittel- or a Myers-Saito-type cyclization was triggered. The 6-endo-dig Myers-Saito-type cyclization gave access to benzo[b]fluorenes, while the Schmittel pathway (5-exo-dig) delivered benzofulvenes as final products. In special cases a yet unknown pathway was opened by the ambiphilic nature of the allene moiety. In these cases completely different products were obtained by the nucleophilic attack of the alkyne moiety onto the allene that can also act as an electrophile. Mechanistic studies revealed that diradical pathways can be ruled out for this type of tandem cyclization reactions and it is shown that both steps of the reaction cascade are catalyzed by the gold complex.
- Rettenmeier, Eva,Hansmann, Max M.,Ahrens, Alexander,Rübenacker, Katharina,Saboo, Tapish,Massholder, Joy,Meier, Christian,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 14401 - 14409
(2015/10/05)
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- Bioinspired intramolecular diels-alder reaction: A rapid access to the highly-strained cyclopropane-fused polycyclic skeleton
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A bioinsipred gold-catalyzed tandem Diels-Alder/Diels-Alder reaction of an enynal and a 1,3-diene, forming the highly-strained benzotricyclo[3.2.1.0 2,7]octane skeleton, was reported. In contrast, a Diels-Alder/Friedel-Crafts tandem reaction occurred instead when silver salts were used as the catalyst. Although both reactions experienced the similar Diels-Alder reaction of a pyrylium intermediate with a 1,3-diene, they have different reaction mechanisms. The former proceeded with a stepwise Diels-Alder reaction, while the latter one with a concerted one. Mother nature knows best! A gold-catalyzed reaction of enynals and 1,3-dienes, giving rapid access to the highly strained benzotricyclo[3.2.1.02,7]octane skeleton, is reported (see scheme; QMD=quinodimethane). Owing to the mild reaction conditions, excellent substrate scope, and high functional-group tolerance, this system holds potential for the construction of complex molecules with the tricyclo[3.2.1.02,7]octane skeleton. Copyright
- Zhu, Shifa,Guo, Zhengjiang,Huang, Zhipeng,Jiang, Huanfeng
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supporting information
p. 2425 - 2430
(2014/03/21)
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- Antimycobacterial activity evaluation, time-kill kinetic and 3D-QSAR study of C-(3-aminomethyl-cyclohexyl)-methylamine derivatives
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A series of C-(3-aminomethyl-cyclohexyl)-methylamine derivatives were synthesized and evaluated for their antitubercular activity. Some of the compounds exhibited potent activity against Mycobacterium tuberculosis H37Rv. One of the compound having t-butyl at para position of the benzene ring showed excellent activity even better than the standard drug ethambutol with MIC value 1.1 ± 0.2 μM. The time-kill kinetics study of two most active compounds showed rapid killing of the M. tuberculosis within 4 days. Additionally atom-based quantitative structure-activity relationship (QSAR) model was developed that gave a statistically satisfying result (R2) = 0.92, Q2 = 0.75, Pearson-R = 0.96 and effectively predicts the anti-tuberculosis activity of training and test set compounds.
- Kumar, Deepak,Raj, K. Kranthi,Bailey, Maiann,Alling, Torey,Parish, Tanya,Rawat, Diwan S.
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supporting information
p. 1365 - 1369
(2013/03/14)
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- One-pot synthesis of dihydrobenzo[4,5][1,3]oxazino[2,3-A] isoquinolines via a silver(I)-catalyzed cascade approach
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An efficient approach for the synthesis of biologically interesting fused tetracyclic isoquinolines in high yields and with a broad substrate scope has been developed. The strategy features an AgNO3 catalyzed 'one-pot' cascade process involving formation of two new C-N bonds and one new C-O bond.
- Jiang, Baifeng,Zhou, Yu,Kong, Qingya,Jiang, Hualiang,Liu, Hong,Li, Jian
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p. 814 - 831
(2013/04/10)
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- Gold-catalyzed reactions of enynals/enynones with norbornenes: Generation and trapping of cyclic o-quinodimethanes (o-QDMs)
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Fan-like structures: An efficient AuIII-catalyzed method to generate the highly reactive cyclic o-quinodimethane (o-QDM) species from easily available enynals or enynones is presented (see scheme). This method produced a variety of structurally unique fan-like products with the advantages of mild reaction conditions, excellent diastereoselectivities, and high functional-group tolerance. Copyright
- Zhu, Shifa,Zhang, Zhicai,Huang, Xiaobing,Jiang, Huanfeng,Guo, Zhengjiang
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supporting information
p. 4695 - 4700
(2013/05/09)
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- Palladium-catalyzed C-H oxidation of isoquinoline N-oxides: Selective alkylation with dialkyl sulfoxides and halogenation with dihalo sulfoxides
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A novel palladium-catalyzed C-H oxidation of isoquinoline N-oxides has been developed for regioselectively synthesizing substituted isoquinolines. The method represents the first example of using dialkyl sulfoxides as the alkyl sources for the construction of 1-alkylated isoquinolines. Moreover, the regioselective halogenation of isoquinoline N-oxides is also successful using dihalo sulfoxides as the halide sources. Copyright
- Yao, Bo,Song, Ren-Jie,Liu, Yan,Xie, Ye-Xiang,Li, Jin-Heng,Wang, Meng-Ke,Tang, Ri-Yuan,Zhang, Xing-Guo,Deng, Chen-Liang
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supporting information; scheme or table
p. 1890 - 1896
(2012/09/22)
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- An efficient route to polysubstituted tetrahydronaphthols: Silver-catalyzed [4+2] cyclization of 2-alkylbenzaldehydes and alkenes
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Silver bullet: A methodology for stereoselective synthesis of polysubstituted tetrahydronaphthols catalyzed by [Ag+]/NPO has been developed. The reactions proceeded through an unprecedented [4+2] cyclization of 2-(2-formylphenyl)ethanone and an alkene, in both inter- and intramolecular fashion. NPO=pyridine N-oxide. Copyright
- Zhu, Shifa,Liang, Renxiao,Jiang, Huanfeng,Wu, Wanqing
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supporting information
p. 10861 - 10865
(2013/01/15)
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- Gold(I)- and Yb(OTf)3-Cocatalyzed rearrangements of epoxy alkynes: Transfer of a carbonyl group in a five-membered carbocycle
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We report here the intramolecular reactions between α,β-epoxy ketones and alkynes cocatalyzed by gold(I) and Yb(OTf)3. This new catalytic system based on a combination of gold(I) and Yb (OTf)3 allows facile transformation of epoxy alkynes to give novel indene derivatives in moderate to good yields under mild conditions. Moreover, we describe here the first observation of a transfer of a carbonyl group in a five-membered carbocycle during gold-catalyzed reactions. This proposed mechanism is corroborated by isotope-labeling experiments (D and 13C). Furthermore, the probable role of each catalyst in this interesting domino reaction has been examined by 31P NMR experiments. The utilization of gold catalysts combined with rareearth metal salts offers a new concept for the design of catalyst combinations for domino or cascade reactions.
- Dai, Lun-Zhi,Shi, Min
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supporting information; experimental part
p. 2496 - 2502
(2010/06/20)
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- Microwave-promoted synthesis of N-heterocycles by tandem imination/ annulation of γ- and δ-ketoalkynes in the presence of ammonia
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The synthesis of 3-substituted l-methylpyrrolo[l,2-a]pyrazines and 3-substituted isoquinolines was achieved by the intramolecular cyclisation of 2-acetyl-l-propargylpyrroles and 2-alkynylbenzaldehydes, respectively, in the presence of ammonia under microwave heating. The tandem imination/annulation of 2-alkynylbenzaldehydes was easily accomplished under standard conditions, while TiCl4 was used to achieve pyrrolo[l,2-a]pyrazines. The reaction mechanism and the regioselectivity were discussed on the basis of theoretical calculations and spectroscopic data. Wiley-VCH Verlag GmbH & Co. KGaA.
- Alfonsi, Maria,Dell'Acqua, Monica,Facoetti, Diego,Arcadi, Antonio,Abbiati, Giorgio,Rossi, Elisabetta
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experimental part
p. 2852 - 2862
(2009/09/06)
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- Facile synthesis of polycyclic fluorene derivatives via a palladium-catalyzed coupling, propargyl-allenyl isomerization and schmittel cyclization sequence
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A stepwise process involving Sonogashira coupling, propargyl-allenyl isomerization and Schmittel cyclization has been realized, leading to an efficient synthesis of polycyclic fluorene derivatives from readily available starting materials. The reaction features the formation of three new carbon-carbon bonds to construct the benzene unit together with an efficient assembly of three or four rings in a single operative step.
- Shen, Ruwei,Chen, Linzhu,Huang, Xian
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supporting information; experimental part
p. 2833 - 2838
(2010/03/25)
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- Gold catalysis: Synthesis of 3-acylindenes from 2-alkynylaryl epoxides
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A series of 2-alkynylaryl epoxides were prepared by a sequence of Sonogashira coupling, Wittig olefination and epoxidation or a Darzens' glycid ester synthesis. The conversion of these substrates with gold(I) catalysts furnished 3-acylindenes and, in occa
- Hashmi, A. Stephen K.,Buehrle, Miriam,Salathe, Ralph,Bats, Jan W.
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supporting information; experimental part
p. 2059 - 2064
(2009/08/07)
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- PtBr2-catalyzed consecutive enyne metathesis-aromatization of 1-(1-methoxy-but-3-enyl)-2-(1-alkynyl)benzenes: Dual role of the Pt catalyst
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(Chemical Equation Presented) 1,7-Enynes 1, connected through an aromatic ring and bearing a leaving methoxy group at the 4-position, underwent the PtBr2-catalyzed enyne metathesis followed by aromatization in one pot to afford vinyl naphthalen
- Bajracharya, Gan B.,Nakamura, Itaru,Yamamoto, Yoshinori
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p. 892 - 897
(2007/10/03)
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- The cyclization reaction of ortho-ethynylbenzaldehyde derivatives into isoquinoline derivatives
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In order to elucidate the reaction mechanism of the cyclization between an ethynyl group and an imino group at the ortho-position on an aromatic ring to afford isoquinolines, reaction of 2-ethynylbenzaldehydes under various conditions was examined. It is concluded that reaction proceeds via an ionic process and the isoquinoline 4-hydrogen atom derives from the solvent. In addition, it was found that 2-ethynylbenzaldehyde O-methyloximes underwent cyclization in the presence of primary and secondary alcohols to give 3- substituted isoquinolines.
- Sakamoto, Takao,Numata, Atsushi,Kondo, Yoshinori
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p. 669 - 672
(2007/10/03)
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- General Preparation of 3-Alkyl-1-Naphthols
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Potassium enolates derived from readily available o-alkynylacetophenones undergo intramolecular cycloaromatization on heating to afford 3-alkyl-1-naphthols in good yields. - Key words: Cycloaromatization, enynone, ynenone, 3-alkyl-1-naphthol.
- Makra, Ferenc,Rohloff, John C.,Muehldorf, A. V.,Link, John O.
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p. 6815 - 6818
(2007/10/02)
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- Synthesis of Analogues of Arachidonic Acid as Potential Inhibitors of Leukotriene Biosynthesis
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A versatile route to 1,2-disubstituted aromatic analogues of arachidonic acid of formulae (5) and (6) has been established involving the stepwise cross-coupling of alkynes to 1,2-dibromobenzene.Subsequent reduction allows good control over the degree of u
- Buckle, Derek R.,Fenwick, Ashley E.
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p. 477 - 482
(2007/10/02)
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