Novel synthesis of dihydropyrans and 2,8-dioxabicylo[3.3.0]oct-3-enes using Mn(III)-based oxidative cyclization

The Mn(III)-based reaction of 1,1-disubstituted alkenes with 2-(2-oxoethyl)malonates and 3-acetylpentane-1,4-diones gave novel substituted dihydropyrans and 2,8-dioxabicyclo[3.3.0]oct-3-enes in good yields, respectively. These routes rely on the nucleophilic character of the carbonyl-oxygen atoms of the malonates and pentanediones used to obtain the products by a cycloaddition reaction or cycloaddition-tandem cyclization reactions.     

Microwave assisted synthesis of 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones using Mn(OAc)3

2-Hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one 2a and 7-hydroxy-5H-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-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-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®.     

A NOVEL SYNTHESIS OF 2-SUBSTITUTED-4H-THIENO [2,3-d][1,3] OXAZIN-4-ONE AND 2,3-DISUBSTITUTED THIENO [2,3-d]PYRIMIDIN-4(3H)-ONE DERIVATIVES

Abstract

The synthesis of acetic 2-{[1-methyl-2-(4-oxo-5,6,7,8-tetrahydro-4H-benzo [4,5]-thieno [2,3-d] [1,3-oxazin-2-yl)ethylidene]amino}-4,5,6,7-tetrahydrohenzo[b]thiophene ?3-carboxylic acid anhydride 5 and 2-(oxopropyl)-5,6,7,8-tetrahydro-4H-benzo-[4,5] thieno[2,3-d][1,3]oxazin-4-one 7, has been achieved in three steps from ethyl 2-amino-4,5,6,7-tetrahydrobenzo(b]thiophene-3-carboxlate 1 via the reaction with ethyl acetoacetate followed by hydrolysis and acetic anhydride-induced cyclization. The 2-substituent in compound 5 has two functional groups i.e. active methylene and acid anhydride which are suitably located for intramolecular transformation. Thermal and/or base catalyzed intramolecular cyclization of 5 afforded 2-(4-acetoxy-(hydroxyl)-2-methyl-5,6,7,8-tetrahydrobenzo[4,5] thieno[2,3-b]pyridin-3-yl)-5,6,7,8- tetrahydro-4H-benzo[4,5]thieno[2,3-d] [1,3]oxazin-4-one 10 and 9 respectively. Treatment of 5 with hydrazine hydrate, aromatic and/or heterocyclic amines induced the same intramolecular cyclization with a concomitant oxazine-pyrimidine interconversion to give 3-amino(aryl or heteryl)-2-(4-hydroxy-5,6,7,8-tetrdhydrobenzo-[4,5]thieno[2,3-b]pyridin-3-yl)-3,4,5,6,7,8-hexahydrobenzo[4,5] thieno[2,3-d] pyrimid in-4-one 11–14 respectively.     

Synthesis and Crystal Structure of 4-(Dichloroacetyl)-1-oxa-4-azaspiro[4.5]decane

<正>The title compound 4-(dichloroacetyl)-1-oxa-4-azaspiro[4. 5] decane (CAS number 71526-07-3, C10H15Cl2NO2, Mr= 252.13) was obtained by the reaction of dichloroacetic acid with 1-oxa-4-azaspiro[4. 5] decane. The crystal is of monoclinic, space group P21ln with the unit cell constants: a = 5.9619(4),b= 10.0066(8), c = 20.0986(4) A,β = 90.194(3)°, V= 1199(4) A3,Z = 4, Dc= 1.397 g/cm3, F(000) = 528, μ(MoKα) = 0.522 mm-1, R = 0.0611 and wR = 0.1656 for 1276 observed reflections (I > 2σ(I)). X-ray analysis reveals that the cyclohexyl adopts a chair conformation and the compound is a chiral one.     

Studies on the esterifications of 9-（hydroxyimino）-4-methyl-8,9-dihydrofuro[2,3-h]chromen-2-one with acid chlorides under different conditions

The esterifications of 9-（hydroxyimino）-4-methyl-8,9-dihydrofuro[2,3-h]chromen-2-one （4） with acid chlorides afforded normal oxime-esters 3a-e in 35-78% yields in presence of excessive 4-dimethylaminopyridine as the acid scavenger, whereas the reactions gave unexpected 8-substituted products N-（8-chloro-4-methyl-2-oxo-2H-furo-[2,3-h]chromen-9-yl）amides （5a-c） and 4-methyl-2,9-dioxo-8,9-dihydro-2H-furo[2,3-h]chromen-8-ylcarboxyloates （6d-e） by using excessive acid chlorides. The structures of 10 new compounds were determined by 1H NMR, 13C NMR, MS and HRMS, and the possible mechanism for the formation of unexpected products 5a--c and 6d-e was also proposed.     

Synthesis of novel coumarinyl-pyrido[2,3-d]pyrimidine-2,4-diones using task-specific magnetic ionic liquid, [AcMIm]FeCl4 as catalyst

Abstract

An acid-functionalized magnetic ionic liquid, 1-acyl-3-methylimidazolium tetrachloroferrate, [AcMIm]-FeCl₄ has been utilized for the synthesis of a series of novel highly functionalized coumarinyl-pyrido[2,3-d]pyrimidine-2,4-dione derivatives (3a-3l) by the reactions of various 3-chloro-3-(2-oxo-2H-chromen-3-yl)acrylaldehydes (1) with functionalized aryl, 6-aminouracils. The major significant of the present procedure is the use of task-specific acidic ionic liquid which act as catalyst as well as reaction medium and thus avoiding use of organic solvent and/or protic acid catalyst. The other major advantages of the protocol are (i) shorter reaction time (1?h), (ii) easy work up procedure, (iii) excellent yields of products (91-94%), and (iv) recyclability of catalyst. The compounds (3a-3l) were identified using FT-IR, ¹H NMR, and ¹³C NMR and mass spectroscopic studies.     

新型2-氨基-呋喃并[2,3-d]嘧啶-4(3H)-酮衍生物的合成及抗肿瘤活性

报道应用aza-Wittig反应,采用易得的原料,在温和的条件下,以78%～90%的产率有效的合成了新型2-氨基-呋喃并[3,2-d]嘧啶-4(3H)-酮衍生物5,其结构经IR,1H NMR,MS和元素分析确认.为进一步得到结构确认,化合物5c经X射线衍射分析证实.运用噻唑蓝(MTT)标准法对化合物5进行了体外抗肿瘤活性的测定,其中5f对肺癌细胞A459的IC50值为18.4μmol/L,显示出潜在良好的抗肿瘤活性.     

Reaction of ene-bis(phosphinylallenes): [2+2] versus [4+2] cycloaddition

Reaction of ene-bis(phosphinylallenes), derived from ene-bis(propargyl alcohols) and chlorodiphenylphosphine, was investigated. Benzene-bridged bis(phosphinylallenes) exclusively gave intramolecular [2+2] cycloadducts in the presence of dimethyl fumarate in sharp contrast to the reaction of benzene-bridged bis(sulfinylallenes), which gave the corresponding [4+2] cycloadducts. On the other hand, substituted ethylene- or five-membered heterocycle-bridged bis(phosphinylallenes) provided [4+2] cycloadducts. Reaction of benzene-bridged diallene bearing both a sulfinyl group and a phosphinyl group on the two allenyl groups was also described.     

Manganese(III)-based oxidation of 2,4-piperidinediones in the presence of alkenes

The manganese(III)-catalyzed aerobic oxidation of 2,4-piperidinediones was performed in the presence of alkenes at room temperature, producing 1-hydroxy-8-aza-2,3-dioxabicyclo[4.4.0]decan-7-ones in excellent yields. On the other hand, the 6-acetoxy-3-aza-7-oxabicyclo[4.3.0]nonan-2-ones were obtained by the oxidation of the 2,4-piperidinedione-3-carboxylates with manganese(III) acetate in the presence of alkenes at elevated temperature under an argon atmosphere. A similar oxidation using decarboxylated 2,4-piperidinediones produced the 2,3,6,7-tetrahydrofuro[3,2-c]pyridin-4(5H)-ones and/or 2,3,6,7-tetrahydrofuro[2,3-b]pyridin-4(5H)-ones in good yields. The structure determination and the decomposition reaction of the azabicyclic peroxides in acetic acid or acetic anhydride, and the reaction pathway were also described.     

Second-sphere coordination in the complex [Mn(H2O)6]2[thiacalix[4]arene tetrasulfonate]

The title calixarene, dimanganese thiacalix[4]arene tetrasulfonate, was prepared and its crystal structure was determined. [Mn(H₂O)₆]₂[thiacalix[4]arene tetrasulfonate]·0.5H₂O crystallizes in the monoclinic system, P2(1)/m space group, with a=13.014 (6), b=14.146 (9), c=13.184 (7) Å, β=113.307 (10)°, V=2229 (2) Å³ and Dc=1.710 gcm⁻³, Z=2. The title calixarene exists in the solid state as bilayer structure. The hydrophobic organic layer consists of thiacalix[4]arene tetrasulfonate in an up-down fashion, whereas, the hydrophilic inorganic layer consists of hexaaquamanganese (II) which is linked to the former through a second-sphere coordination.     

Functionalized naphthol[2,3-h] quinoline-7,12-diones

The addition of secondary and primary amines to ethyl (1-amino-9,10-anthraquinon-2-yl)propynoate affords an easily separable mixture of the corresponding ethyl 3-dialkylaminoor 3-alkylamino-3-(1-amino-9,10-anthraquinon-2-yl)acrylate and 3-dialkylamino- or 3-alkylaminonaphthol[2,3-h]quinoline-2(1H), 7,12-trione (in ∼4: 1 ratio). Intramolecular cyclization of the resulting substituted ethyl acrylates results in the formation of 4-dialkylaminoor 4-alkylamino-2-chlorinated pyridine rings. Subsequent nucleophilic substitution of the chlorine atom gives 2-functionalized 4-dialkylamino- or 4-alkylaminonaphtho[2,3-h]quinoline-7,12-diones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2327–2332, November, 1998.     

One-pot three-component regioselective synthesis of linear naphtho[2,3-b]-furan-4,9-diones

The regioselective three-component condensation reaction of 2-hydroxy-1,4-naphthoquinone with isocyanides in the presence of a variety of aldehydes offers an easy one-pot access to linear naphtho[2,3-b]-furan-4,9-dione derivatives. This method has the advantage of good yields, high regioselectivity, and uses readily accessible substrates and reagents. The elucidation of regiochemistry has been accomplished by X-ray determination of some representative compounds.     

Formation of 1,2-dioxolanes using Mn(III)-based reaction of various arylacetylenes with 2,4-pentanedione and related reaction

The manganese(III)-based aerobic oxidation of arylacetylenes with 2,4-pentanedione at ambient temperature unexpectedly gave the 1,2-dioxolane derivatives in moderate yields together with a small amount of the oxiranes. The 1,2-dioxolanes underwent silica gel-assisted contraction to quantitatively give the oxiranes. The reaction pathway for the formation of the 1,2-dioxolanes and the by-product was discussed.     

Facile Synthesis of Naphtho[2,3‐d]thiazoles,Naphtho[2,3‐e][1,3,4]thiadiazines and Bis(naphtho[2,3‐d]thiazolyl)copper(II) Derivatives from Heteroylthiosemicarbazides

A one step synthesis protocol for the conversion of heteroylthiosemicarbazides and 2,3‐dichloro‐1,4‐naphthoquinone to naphtho[2,3‐d]thiazoles, naphtho[2,3‐e][1,3,4]thiadiazines as well as bis(naphtho[2,3‐d]thiazolyl)copper(II) derivatives is described. The products were conclusively confirmed by single crystal X‐ray analyses. A mechanism for the formation of the products is presented.     

Facile synthesis of polysubstituted 2,3-dihydropyrroles and pyrroles from Mn(OAc)3-promoted oxidative cyclization of alkenes with amines/alkyne esters or enaminone esters

A novel oxidative cyclization of alkenes with amines/alkyne esters or enaminone esters can be efficiently promoted by Mn(OAc)₃, furnishing a series of polysubstituted 2,3-dihydropyrroles in moderate to excellent isolated yields (75–91%). Afterward addition of a suitable oxidant such as K₂S₂O₈ can furnish efficient synthesis of the corresponding polysubstituted pyrroles in a one-pot pathway.     

Chemistry of acyl(imidoyl)ketenes. 7. Synthesis and thermolysis of 5-aryl-4-quinoxalinyl-2,3-dihydrofuran-2,3-diones

3-Aryl-Z-2-aroylmethylidene-1,2-dihydroquinoxalines react with oxalyl chloride to form 3-aryl-2-(2-aryl-4,5-dioxo-4,5-dihydro-3-furyl)quinoxalines, whose thermal decarbonylation generate 5-aryl-2-3(arylquinoxalin-2-yl)-4-aroyl-3-aroyloxy-1H-pyrido[1,2-a]quinoxalin-1-ones. The crystal and molecular structures of one of them (Ar = Ph) were established by X-ray diffraction analysis.     

Catalyst-free synthesis of novel 4H-indeno[1,2-b]furan-4-ones and furo[2,3-d]pyrimidines in water

An operationally simple, catalyst-free, and efficient protocol for the synthesis of novel 4H-indeno[1,2-b]furan-4-one and furo[2,3-d]pyrimidine derivatives by a one-pot reaction of 2-aminopyridines, 1,3-indandione, or barbituric acid and phenylglyoxal monohydrate in water at reflux, involving domino aldol condensation, Michael addition, and ring-closing reactions is described. This transformation has several advantages, including high yield, short reaction duration, simple workup, and simple purification.     

Facile Synthesis of 2-Alkylthio-5,6,7,8-tetrahydrobenzothieno[2,3-d]pyrimidin-4(3H)-ones

Isothiocyanate 2, obtained from aza-Wittig reaction of iminophosphorane 1 with CS₂, reacted with amine to give 2-thioxo-2,3,5,6,7,8-hexahydrobenzothieno[2,3-d]pyrimidin-4(1H)-ones 4 in the presence of sodium ethoxide. S-Alkylation of 4 produced 2-alkylthio-5,6,7,8-tetrahydrobenzothieno[2,3-d]pyrimidin-4(3H)-ones 5 in good yields.     

Mn(III)-based oxidative tandem free-radical cyclizations of methylenecyclopropanes with substituted dicarbonyl compounds

Manganese(III) acetate-mediated tandem radical cyclization reactions of methylenecyclopropanes with methyl substituted dicarbonyl compounds in acetic acid give dihydronaphthalene derivatives in moderate yields under mild conditions.