Search

ABSTRACT The oxidation of 5,5′‐(methylene)bis(6‐hydroxy‐1,3‐dimethylpyrimidine‐2,4(1H,3H)‐dione) monopiperidinium salts with Mn(OAc)3•2H2O was carried out in boiling MeCN, producing 2,4,9,11‐tetramethyl‐2,4,9,11‐tetraazadispiro[5.0.57.16]tridecane‐1,3,5,8,10,12‐hexaones in high yields. A similar reaction using 4,4′‐(methylene)bis(1,2‐diphenylpyrazolidine‐3,5‐dione)s gave 2,3,8,9‐tetraphenyl‐2,3,8,9‐tetraazadispiro[4.0.46.15]undecane‐1,4,7,10‐tetraones in good yields. The structure determination and the reaction mechanism for the formation of the unique tetraazadispiro(cyclopropane)s are discussed. [ABSTRACT FROM AUTHOR]

The Mn(III)-based oxidation of 1,3-indanedione (1) with 1,1-diarylethenes 2a–c effectively proceeded in boiling AcOH to produce 2,2-bis(vinyl)indanediones 5a–c and 1,2'-spirobi[indene]-1',3'-diones 6a–c via the formation of 2,2-bis(2-acetoxyethyl)indanedione 3 and acetoxyindeno[1,2-b]furan-4-one 4 intermediates. On the other hand, the Mn(III)-based aerobic oxidation of 1a with 2a at room temperature resulted in bis(endoperoxide) 8a and endoperoxypropellane 9a via the production of mono(endoperoxide) 7a. The plausible reaction pathways were also discussed. [ABSTRACT FROM AUTHOR]

Kocaeli University, Kabaoğlu, 41380, In this work, furo[2,3‐d]pyrido[1,2‐a]pyrimidin‐4‐ones were obtained by microwave assisted radical cyclizations of 2‐hydroxy‐4H‐pirido[1,2‐a]pirimidin‐4‐ones with conjugated alkenes and phenylacetylene via Mn(OAc)3. Conventional heating and microwave irradiated reaction types were compared using parameters like temperature, time and molar ratios to determine best reaction condition. Obtained compounds were purified by chromatographic methods and characterized by spectroscopic techniques (1H NMR, 13C NMR, HRMS, FTIR). Also, to determine the exact configuration and regioselectivity of isolated compounds, XRD analysis were performed. [ABSTRACT FROM AUTHOR]

Oxidation of geranyl acetone derivatives with ceric ammonium nitrate (CAN) and Mn(OAc)3 afforded tricyclic and bicyclic compounds as well as hydroxy and nitro compounds as a result of one-electron oxidation followed by carbon–carbon bond formation. This is the first example of radical cyclization (formed by one-electron oxidation) of geranyl acetone derivative 1 and its isomer 4 to give tri- and bicyclic products with carbon–carbon bond formation. [ABSTRACT FROM AUTHOR]

An efficient method for the preparation of 4-oxo-4,5,6,7-tetrahydroindoles was successfully applied to the synthesis of N-substituted 4-oxo-4,5,6,7-tetrahydroindoles (4) and (5) for the first time. Manganese(III) acetate-mediated acetoxylation of (2) produced 4,5,6,7-tetrahydro-4-oxo-7,7-dimethyl benzofuran-5-yl acetate (3) for the first time in the literature. Then 4,5,6,7-tetrahydro-4-oxo-7,7-dimethyl benzofuran-5-yl acetate was converted to its indole derivative (4) via benzyl amine. Thus, 1-benzyl-5-hydroxy-7,7-dimethyl-6,7-dihydro-1H-indol-4(5H)-one (4) was obtained in good yields. Furthermore, biotransformation of pharmacologically interesting compounds such as 5-hydroxy-7,7-dimethyl-6,7-dihydro-1H-indol-4-(5H)-one (5) were also obtained by biotransformation reaction using Aspergillus niger. [ABSTRACT FROM AUTHOR]

Manganese(III) acetate-mediated radical cyclization of N -substituted acrylamides with cyclohexane-1,3-diones gives 4-oxo-2,3,4,5,6,7-hexahydrobenzofuran-2-carboxamides and unexpected tricyclic 1,1a,5,6-tetrahydro-2 H -cyclopropa[ c ]indole-2,7(3 H)-diones. The structure of one representative tricyclic compound was confirmed by X-ray analysis. The reaction mechanism was examined employing some structural analogues of the reactants. [ABSTRACT FROM AUTHOR]

In this study, the radical cyclization reactions of cyclic 1,3-dicarbonyl compounds (1a-c) and α,β-unsaturated alcohols (2a-d) through Mn(OAc)3 were performed. A series of biologically interesting dihydropyrans (3-5) and dihydrofurans (6-18) were synthesized as a result of these reactions. Spiro compounds (19-20) were obtained from the reactions of 1,3-dicarbonyl compounds and (E)-2,4-diphenyl-but-3-en-2-ol (2e). The unique structure of compound 19 was also confirmed by X-ray crystallography. In addition, the antibacterial activities of synthesized compounds were screened against some bacteria. Their zone diameters showed better results than some known antibiotics. [ABSTRACT FROM AUTHOR]

Abstract: A cobalt‐catalyzed sp2 C−H acetoxylation of amides having 8‐aminoquinoline as a directing group has been achieved using manganese(III) acetate both as an oxidant and an acetoxy source. Operational simplicity, broad range of functional group tolerance, use of an earth abundant first row transition metal, and, most importantly, exploitation of an unprecedented acetoxy source are the key features. The method is scalable and does not require any additive. The mechanism of the reaction has been established by conducting a series of experiments. [ABSTRACT FROM AUTHOR]

In continuation to our previous findings on amidoximes' antiparasitic activities, a new series of 23 original derivatives was designed and obtained by convergent synthesis. First, new terminal alkenes were synthesized by cross-coupling reaction. Then, cyclization was performed between terminal alkenes and β-ketosulfones using manganese(III) acetate reactivity. Twenty-three amidoximes were tested for their in vitro activity against Leishmania amazonensis promastigotes and their toxicity on murine macrophages. Seven of the tested compounds exhibited an antileishmanial activity at lower than 10 μM with moderate to low toxicity. Six of these molecules showed activity at lower than 10 μM against promastigotes and toxicity at higher than 50 μM were selected and evaluated for their activity against intracellular Leishmania amazonensis amastigotes. Modulating chemical substituents in position 2 of dihydrofuran highly influenced their antileishmanial activities. The introduction of a methyl or trifluoromethyl group on the benzene ring of the benzyl group had a positive influence on activity without significantly increasing toxicity ( 52, 59, 60 ). [ABSTRACT FROM AUTHOR]

The present work reports a simple and efficient method for the sulfenylation of a wide variety of indoles with aryl, benzothiazolethiols using manganese(III) acetate promoted free radical reaction. This method is selective at the C3 position of indoles and offers several advantages such as broad substrate scope, functional group tolerance (bromo, carboxylic acid, methoxy, difluoromethoxy, ester groups) and gives the required products in good to excellent yields. The experimental simplicity makes it a useful and attractive approach for the synthesis of 3-arylsulfenylindoles. The compounds 1-12 are evaluated for the anti-bacterial agents. Most of them exhibited promising activities. [ABSTRACT FROM AUTHOR]

In this study, the manganese(III) acetate mediated radical addition-cyclization reactions of ferrocene substituted alkenes and active methylene compounds were carried out. The regio- and stereoselective radical cyclization reactions of (E)-styrylferrocene ( 1a ) and active methylene compounds ( 2a-g ) gave trans -5-ferrocenyl-4-phenyl-4,5-dihydrofuran compounds as the sole products. The reactions of 1-ferrocenyl-1-aryl(heteroaryl)ethenes ( 1b-e ) and active methylene compounds ( 2a-f ) via Mn(OAc) 3 led to furan and benzofuran derivatives ( 10–33 ) in mid-good yields (up to 75%). Surprisingly, ferrocene substituted allylidene derivatives were obtained from the Mn(OAc) 3 mediated reactions of 1-aryl-1-ferrocenylethene ( 1b-d ) and 1,3-dimethylbarbituric acid ( 2g ). The uses of ferrocene substituted alkenes in manganese(III) acetate mediated radical reactions is the first example in this field as far as we know. [ABSTRACT FROM AUTHOR]

2-Oxa-7-azaspiro[4.4]nonane-8,9-diones were newly synthesized in good yields by the Mn(III)-based reaction of a mixture of 1,1-diarylethenes and 4-acylpyrrolidine-2,3-diones. Under the stated reaction conditions, the pyrrolidinedione ring remained intact and became one of the two rings of the 2-oxa-7-azaspiro[4.4]nonanedione scaffold. The procedure was simple and the product was easily separated. The structure determination and the mechanism for the formation of the 2-oxa-7-azaspiro[4.4]nonanediones were also discussed. [ABSTRACT FROM AUTHOR]

2-Hydroxy-4 H -benzo[4,5]thiazolo[3,2- a ]pyrimidin-4-one 2a and 7-hydroxy-5 H -thiazolo[3,2- a ]pyrimidin-5-one 2b , were obtained in high yields under mild conditions from the cyclization reactions of bis-(2,4,6-trichlorophenyl) malonate and 2-aminobenzothiazole or 2-aminothiazole, respectively. A new class of compounds, 2,3-dihydro-4 H -benzo[4,5]thiazolo[3,2- a ]furo[2,3- d ]pyrimidin-4-ones and 6,7-dihydro-5 H -furo[2,3- d ]thiazolo[3,2- a ]pyrimidin-5-ones, were synthesized via the microwave assisted radical addition of compounds 2a and 2b to various alkenes using manganese(III) acetate. A preliminary acetylcholine esterase (AchE) inhibition test of compound 4e showed excellent (92%) inhibitory potential, comparable with the standard drug Donapezil®. [ABSTRACT FROM AUTHOR]

The Mn(III)-based oxidation of 2,7-, 1,8-, and 1,5-disubstituted naphthalenes bearing both the 1,4-dioxa-7,7-diphenylhep-6-enyl and 1,4-dioxa-5,7-dioxooctyl groups gave new [12]naphthalenophanes along with the corresponding diploids via assembly of the dihydrofuran ring. A similar reaction of the 2,6-disubstituted naphthalene having the same substituents did not produce the naphthalenophane, but the diploid, [12,12](2,6)naphthalenophane, was obtained in a small amount. The 2,6-disubstituted naphthalene tethered to the 1,4,7-trioxa-10,10-diphenyldec-9-enyl and 1,4,7-trioxa-8,10-dioxoundecyl groups also underwent the dihydrofuran-clipping reaction to afford a trace amount of the desired [18](2,6)naphthalenophane. The reaction details and the structure determination of the products are described. [ABSTRACT FROM AUTHOR]

A convenient microwave irradiation protocol was utilized for the synthesis of b-ketosulfones 1–5 in good yields. These sulfones reacted with alkenes through a radical oxidative cyclization mediated by Mn(OAc)3. Dihydrofurans 6–10 were obtained in moderate to good yields starting from 1,1-disubstituted alkenes. Dihydrofurans 11–15 were synthesized in moderate yields and unexpected cyclopropanes 16–19 were obtained in low yields starting from 1,2-disubstituted alkenes. This protocol offers access to various dihydrofurans which could be tested for their antiparasitic potential.

Diethyl 2,5-dihydroxy-2,5-bis(trifluoromethyl)tetrahydrofuran-3,4-dicarboxylate has been synthesized for the first time by reaction of lithium 4-ethoxy-1,1,1-trifluoro-4-oxobut-2-en-2-olate with manganese(III) acetate. The structure of its (2S*3S*4S*5S*) stereoisomer has been confirmed by X-ray analysis. [ABSTRACT FROM AUTHOR]

Radical oxidation and addition reactions of anthracene (1), 9-methylanthracene (2) and 9-phenylanthracene (3) were investigated with dimethyl malonate (4) in the presence of ceric ammonium nitrate (CAN) and manganese(III) acetate (Mn(OAc)3). Although mostly anthraquinone derivatives and bianthrone were obtained with CAN, substituted 9,10-dihydroanthracene and 9,10-substituted anthracene derivatives were obtained with Mn(OAc)3. Dimethylmalonyl addition products (5a, 33 % and 5b, 42 %) were obtained in higher yield than quinones (5d, 8 % and 5e, 3 %) using Mn(OAc)3 as oxidant. 9a (96 %) and 9b (84 %) were synthesized in high yield and substitution products (7a, 44 % and 8b, 56 %) were obtained in higher yields than quinones (5d and 5e) using CAN as oxidant. The reactions were carried out in non-acidic medium (dichloromethane and methanol). Based on the structures of the isolated products a mechanism for these transformations was proposed.

A three step synthesis of various thiobarbiturate derivatives 17–24 was established. The first step is mediated by Mn(OAc)3, in order to generate a carbon-carbon bond between a terminal alkene and malonate. Derivatives 1–8 were obtained in moderate to good yields under mild conditions. This key step allows synthesis of a wide variety of lipophilic thiobarbiturates, which could be tested for their anticonvulsive or anesthesic potential.

An effective method for the synthesis of 3,4-disubstituted quinolin-2(1 H )-ones was reported. α-Carbonylalkyl radical, produced by the manganese(III) acetate oxidation of α-substituted N -[2-(phenylethynyl)phenyl]acetamides, undergoes a 6-exo-dig cyclization onto the C–C triple bond efficiently and 3,4-disubstituted quinolin-2(1 H )-ones were produced. Heterocyclic substrates could also be used to generate the corresponding quinolin-2(1 H )-ones smoothly. A variety of functional groups, including methoxycarbonyl, cyano, diethoxyphosphoryl and benzoyl groups, are compatible with the reaction conditions. Under Mn(II)/Co(II)/O 2 conditions, the formation of these quinolin-2(1 H )-ones could also be achieved from the corresponding N -[2-(phenylethynyl)phenyl]acetamides and a catalytic amount of manganese(II) acetate was used. [ABSTRACT FROM AUTHOR]

A simple and short synthesis has been revealed for the preparation of (±) β-(Methoxy-(substitutedphenyl)-methyl)-γ-butyrolactones. The reaction of cinnamyl acetate with Mn(OAc)3 · 2H2O in boiling acetic acid containing acetic anhydride gave the products2and3,which further cyclized in 3% H2SO4/CH3OH to afford the butyrolactones (8a–e), which are intermediates of lignin, in good to moderate yields. [ABSTRACT FROM AUTHOR]

The Mn(III)-based oxidation of a tertiary alkylamine, such as nitrilotris(ethane-2,1-diyl) tris(3-oxobutanoate) (1) with 1,1-diphenylethene (2a), effectively proceeded in an acetic acid–formic acid mixed solvent to give nitrilotris(ethane-2,1-diyl) tris(2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxylate) (3). Other typical Mn(III)-based reactions of variousβ-diketo esters4a–e, 2,4-pentanedione (6a), malonic acid (6b), and diethyl malonate (6c) with 1,1-diarylthenes2a–dwere also investigated in a similar acetic acid–formic acid mixed solvent and the reaction rate was accelerated and the product yield increased. [ABSTRACT FROM PUBLISHER]

A synthetic method of 3-substituted 2-quinolinones from readily available α-substituted N -[( E )-stilben-2-yl]acetamides have been developed. α-Carbonylalkyl radical, produced by the manganese(III) acetate oxidation of N -[( E )-stilben-2-yl]acetamides, undergoes an intramolecular 6-exo-dig cyclization onto the C C bond efficiently and 2-quinolinones was produced. A variety of functional groups, including benzoyl, acetyl, cyano, and ethoxycarbonyl groups, are compatible with the reaction conditions. Under Mn(II)/Co(II)/O 2 conditions, these N -[( E )-stilben-2-yl]acetamides were also converted into the corresponding 2-quinolinones effectively and a catalytic amount of manganese(II) acetate was used. [ABSTRACT FROM AUTHOR]

The manganese(III)-mediated oxidative free-radical reactions of 2-(alkenylamino)-1,4-naphthoquinones are described. The free-radical reaction of 2-(allylamino)-1,4-naphthoquinone with 1,3-dicarbonyl compounds provides a novel method for the synthesis of benzo[f]indole-4,9-diones and benzo[g]quinoline-5,10-diones. The reaction shows high chemoselectivity, depending on the solvents and 1,3-dicarbonyl compounds used. With both 1,3-diones and β-keto esters, in acetic acid, the condensation products, benzo[f]indoles, were generated selectively; in acetonitrile, the [5+1]-cyclization products, benzo[g]quinolines and tetrahydroben-zo[g]quinolines, were produced in high chemoselectivity. With di-ethyl malonate, the [5+1]-cyclization product, the corresponding tetrahydrobenzo[g]quinoline, was produced exclusively. The free-radical reaction of a 2-(vinylamino)-1,4-naphthoquinone with 1,3-dicarbonyl compounds produced benzo[g]quinolines effectively. [ABSTRACT FROM AUTHOR]

Manganese(III) acetate is found to be an efficient catalyst to perform oxidation of 3,5-di- tert -butylcatechol (DTBC) to 3,5-di- tert -butylbenzoquinone (DTBQ) and 2-aminophenol (OAP) to 2-aminophenoxazinone (APX). The k cat values are 1.72(2) × 10 3 and 2.8(2) × 10 2 h −1 for the formation of DTBQ and APX, respectively. The turnover number of APX formation is highest among the synthetic mimics. ESI-MS studies of DTBC oxidation suggest formation of a Mn IV intermediate. Manganese(III) acetate is also capable of oxidative C C bond coupling in sterically hindered phenols to form biaryls in 65–94% yield. [ABSTRACT FROM AUTHOR]

Following the promising antileishmanial results previously obtained in monoamidoxime series, a new series of derivatives was synthesized using manganese(III) acetate, Wittig reactions and Suzuki–Miyaura cross coupling reactions. Pharmacomodulation in R 1 , R 2 or R 3 substituents on the amidoxime structure is shown to influence antiprotozoan activity in vitro : a monosubstituted phenyl group in R 1 ( 32 – 35 ) led to an activity against Leishmania donovani promastigotes ( 32 , IC 50 = 9.16 μM), whereas a polysubstituted group ( 36 – 37 ) led to an activity against Plasmodium falciparum ( 36 , IC 50 = 2.76 μM). Modulating chemical substituents in R 2 and R 3 only influenced the antiplasmodial activity in vitro . This suggests that the amidoxime scaffold has properties that could make it a promising new antiparasitic pharmacophore. [ABSTRACT FROM AUTHOR]

6-Phenanthridinephosphonates have interesting biological activities and potential pharmaceutical applications. However, methods for preparing these compounds are very limited. In this report, dialkyl 6-phenanthridinephosphonates were synthesized through Mn(OAc)3-mediated radical phosphonation of 2-isocyanobiaryls in good to excellent yields under relatively mild reaction conditions. As one of its notable features, the radical process allows the direct formation of a PC bond and the construction of a phenanthridine ring in one reaction. [ABSTRACT FROM AUTHOR]

The oxidative cyclization reactions of 1,3-dicarbonyl compounds 1a- 1c and α, β-unsaturated alcohols 2a- 2f with Mn(OAc)3 were performed, leading to dihydrofurans. Treatment of 1a and 1b with 2-methylbut-3-en-2-ol ( 2a) gave dihydrofurans 3aa and 3ba, and dihydropyrans 4aa and 4ba, as unexpected products. While the reaction of 2-methylbut-3-yn-2-ol ( 2b) with acetylacetone ( 1b) yielded a bifuran, ethyl acetoacetate ( 1a) led to a mixture of furan, bifuran, and salicylate derivatives. Besides, surprisingly, styryl-substituted dihydrofurans were obtained from the reactions of 1,3-dicarbonyl compounds and (3 E)-2,4-diphenylbut-3-en-2-ol. The reaction mechanisms were proposed for the formation of the different products, considering intermediates in these reaction mixtures. [ABSTRACT FROM AUTHOR]

A method has been developed for the synthesis of highly functionalized quinolines from readily available N-(2-alkenylaryl)-substituted enamines via a 6-exo-trig radical cyclization of an imine radical. Several useful functional groups including morpholinocarbonyl, benzoyl, and cyano, are compatible with the reaction conditions. Under the Mn(II)/Co(II)/O2 redox system, these N-(2-alkenylaryl)enamines were also converted into the corresponding quinolines effectively. This strategy was further applied to related 1,4-naphthoquinone derivatives, and benzo[b]acridine-6,11-diones were formed in good yields [ABSTRACT FROM AUTHOR]

Manganese(III)-promoted cyclization of N-alkenylmalonamides (= N-alkenylpropanediamides) gave 3-(aryl/(alkylamino)carbonyl) β-lactams as well as 3-(aryl/(alkylamino)thiocarbonyl) β-lactams. The relative configuration of the obtained products was unambiguously determined by X-ray crystallography. The proposed method is very useful for the one-pot synthesis of a number of 3-(aryl/(alkylamino)carbonyl) β-lactams, especially those containing an amino(thiocarbonyl) moiety, which are not selectively accessible by other methods. [ABSTRACT FROM AUTHOR]

The phosphonyl radical generated from the reaction of dimethyl phosphite with manganese(III) acetate adds selectively to the 3-position of pyridin-2-ones or the 5-position of pyrimidin-4-ones to afford phosphonylated products in good yields. [ABSTRACT FROM AUTHOR]

Abstract: p-Toluenesulfonyl radical can be generated by the manganese(III) acetate oxidation of sodium p-toluenesulfinate. The corresponding alkyl radicals could be produced effectively by the p-toluenesulfonyl radical induced radical reaction of allylsulfonyl substituted N-aryl amides. These alkyl radicals undergo 5-exo-trig, 6-endo-trig, or 6-exo-trig cyclization onto the aromatic ring effectively. The product distribution is highly dependent on the substituent of aromatic ring and the stability of radical intermediate. This p-toluenesulfonyl radical induced reaction provides a synthetically useful method for the synthesis of dihydroquinolinones, azaspirocyclic cyclohexadienes, and spirodihydroquinolinones. [Copyright &y& Elsevier]

A convenient microwave irradiation protocol was utilized for the synthesis of β-ketosulfones 1-5 in good yields. These sulfones reacted with alkenes through a radical oxidative cyclization mediated by Mn(OAc)3. Dihydrofurans 6-10 were obtained in moderate to good yields starting from 1,1-disubstituted alkenes. Dihydrofurans 11-15 were synthesized in moderate yields and unexpected cyclopropanes 16-19 were obtained in low yields starting from 1,2-disubstituted alkenes. This protocol offers access to various dihydrofurans which could be tested for their antiparasitic potential. [ABSTRACT FROM AUTHOR]