- Ag(i)-Promoted homo-dimerization of 2-(alk-2-yn-1-onyl)-1-alkynylbenzenesviaa [4 + 2] cycloaddition of benzopyrylium ions: access to structurally unique naphthalenes
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Herein we report a Ag(i)-promoted homo-dimerization of 2-(alk-2-yn-1-onyl)-1-alkynylbenzenes for the synthesis of structurally novel and functionalized naphthalene derivatives. This transformation exhibits a broad scope for the alkyl as well as aryl groups present on alkynes. Observations made from control experiments suggest the possible mechanism as (i) the homo-dimerization of thein situgenerated benzopyrylium ion intermediates through a head-tail [4 + 2] cycloaddition, followed by (ii) the competitive ring-openingvs. decarbonylative aromatization of the adduct to give formylated and deformylated naphthalenes, respectively.
- Baire, Beeraiah,Santhi, Jampani
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supporting information
p. 247 - 251
(2021/12/29)
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- Dual Activity of Grubbs-Type Catalyst in the Transvinylation of Carboxylic Acids and Ring-Closing Metathesis Reactions
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The development of a multifunctional catalyst, which mimics the promiscuity of enzymes, that would catalyze more than one chemical transformation in a single reaction vessel is one of the key points of modern sustainable chemistry. The results of our experiments indicated that Grubbs-type catalysts possess such multitask activity, catalyzing the transvinylation reaction of carboxylic acids without losing their original metathetic activity. This new activity of Grubbs catalysts was evidenced on several examples. It allows us to design a transvinylation/ring-closing metathesis (RCM) cascade reaction leading to the formation of endocyclic enol lactones from unsaturated carboxylic acids in an one-pot procedure. This unique ability of Grubbs catalyst to catalyze multiple mechanically distinct cascade reactions in a chemoselective way offers the new possibility for the synthesis of complex compounds from simple, easily accessible substrates.
- Brodzka, Anna,Koszelewski, Dominik,Ostaszewski, Ryszard,Brodzka, Anna,Ostaszewski, Ryszard
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p. 15305 - 15313
(2020/12/01)
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- Rhodium(I)-Catalyzed Decarbonylative Aerobic Oxidation of Cyclic α-Diketones: A Regioselective Single Carbon Extrusion Strategy
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A rhodium-catalyzed decarbonylative aerobic oxidation of cyclic α-diketones has been developed for the first time, where the regioselective formations of α-pyrones and isocoumarins have been achieved. The current decarbonylative aerobic oxidation pathway proceeds via the C-C bond cleavage followed by a C-O bond formation, representing a biomimetic oxidation approach to unsaturated six-membered cyclic lactones. The unique ability of rhodium catalysts to induce the decarbonylative aerobic oxidation opens up a new synthetic toolbox that utilizes the "regioselective single carbon" extrusion strategy.
- Golime, Gangadhararao,Kim, Hun Young,Oh, Kyungsoo
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p. 942 - 945
(2018/02/22)
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- Reductive electrochemical formation of 6H-dibenzo[b,d]pyran-6-one and 2-benzopyran-1(1H)-one
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In the present Letter several carbolactones (oxidative products) are obtained under aprotic cathodic conditions in the preparative scaled electrolysis of 1,2-quinones in a divided electrochemical cell and in the presence of oxygen. When 9,10-phenanthrenequinone is reduced 6H-dibenzo[b,d]pyran-6-one and [1,1′-biphenyl]-2,2′-dicarboxylic acid are obtained as major products. In the reduction of 1,2-naphthoquinone, 2-benzopyran-1(1H)-one, and 2-(2-carboxyethenyl)-benzoic acid were formed as main products. The proposed mechanism to explain the formation of these and other products, that involves an electron-transfer reaction to the oxygen in air, is now discussed.
- Batanero, Belen,Barba, Fructuoso,Barba, Isidoro,Elinson, Michail N.
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- Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters
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Unprecedented alkylation of silyl enol ethers has been developed by the use of ortho-alkynylbenzoic acid alkyl esters as alkylating agents in the presence of a gold catalyst. The reaction probably proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack on the silyl enol ethers. The generated leaving compound abstracts a proton to regenerate the silyl enol ether structure.
- Aikawa, Haruo,Kaneko, Tetsuro,Asao, Naoki,Yamamoto, Yoshinori
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body text
p. 648 - 652
(2011/08/03)
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- Total synthesis of coriandrin and 7-demethylcoriandrin via a new synthesis of isocoumarins
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Indenone epoxides 8, prepared from the corresponding indenones, have been shown to undergo clean thermal rearrangement to give isocoumarins 10 in high yields. This synthesis of isocoumarins, when applied to oxaindace-none 7, resulted in the total synthesis of coriandrin (1). (C) 2000 Elsevier Science Ltd.
- Mal, Dipakranjan,Bandyopadhyay, Mousumi,Ghorai, Sujit K.,Datta, Kalyani
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p. 3677 - 3680
(2007/10/03)
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- SUBSTITUTED ISOCOUMARINS
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Substituted isocoumarins, their use in inhibiting serine proteases with chymotrypsin-like and elastase-like specificity and their roles as anti-inflammatory agents.
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- THE GENERATION AND PHOTOCHEMISTRY OF INDENONE O-OXIDE AND FLUORENONE O-OXIDE IN LOW TEMPERATURE MATRICES
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The photolysis of diazoindene and diazofluorene at 12 K in N2 matrices containing O2 has been studied, using i.r. spectroscopy.The carbonyl oxides, indenone O-oxide and fluorenone O-oxide, were formed by the reaction of O2 with the corresponding carbenes, and under appropriate conditions could be detected as very photolabile species.Photolysis of indenone O-oxide gave indenone and isocoumarin; similar photolysis of fluorenone O-oxide gave fluorenone and dibenzopyran-6-one.
- Dunkin, Ian R.,Bell, Gordon A.
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p. 339 - 348
(2007/10/02)
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- SYNTHESIS OF ISOCOUMARINS VIA THALLATION-OLEFINATION OF BENZOIC ACIDS
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Benzoic acid and substituted benzoic acids are readily thallated by thallium(III) trifluoroacetate and subsequently reacted with palladium chloride and simple olefins, allylic halides, vinyl halides, or vinyl esters to give isocoumarins.The organic halide reactions are catalytic in palladium. 1,2- and 1,3-dienes also react catalytically to afford 4-alkylidene- and 3-vinyl-3,4-dihydroisocoumarins, respectively.Vinylcyclopropanes also afford 3-vinyl-3,4-dihydroisocoumarins.This highly convenient thallation-olefination approach appears quite general for the synthesis of isocoumarins.
- Larock, R. C.,Varaprath, S.,Lau, H. H.,Fellows, C. A.
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p. 5274 - 5284
(2007/10/02)
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- Syntheses of Fluorescent Dyes, 11. - Rearrangement of Alkoxymethylene- and Aminomethylenehomophthalic Anhydrides into Isocoumarins and Isoquinolinones, resp.
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Homophthalic acid (1) and its anhydride (3,4-dihydro-1H-2-benzopyran-1,3-dione, 2) react with trimethoxymethane in acetic acid anhydride to give 4-methoxymethylenehomophthalic anhydride (3a).This is converted into the enamines 4a-i by reaction with primary or secondary amines and ureas, respectively. 4b,d-i may also be obtained directly from 2 by reaction with a mixture of trimethoxymethane and the corresponding amine (or urea).In alkaline methanol 3a and similarly 4h suffer ring opening to give 5 and 6, respectively. - Treatment of 3a with aqueous sodium hydroxide and subsequent acidification furnishes by a rearrangement reaction the isocoumarin-4-carboxylic acid (7a) together with some of its decarboxylation product 7b, probably via an open ring intermediate of type A.Better yields of 7a are obtained by rearrangement performed in concentrated hydrochloric acid. - Similarly, compounds 4 rearrange to form the isoquinoline-4-carboxylic acids 8a-d. - Starting from homophthalic acid (1), these rearrangements offer a straightforward route to obtain fluorescent isocoumarin as well as isoquinolinone derivatives.
- Wolfbeis, Otto S.
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p. 819 - 827
(2007/10/02)
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