Electrophilicity of 5-benzylidene-1,3-dimethylbarbituric and -thiobarbituric acids

The kinetics of reactions of acceptor-stabilized carbanions 2a-m with benzylidenebarbituric and -thiobarbituric acids 1a-e has been determined in a dimethyl sulfoxide solution at 20 degrees C. Second-order rate constants were employed to determine the electrophilicity parameters E of the benzylidenebarbituric and -thiobarbituric acids 1a-e according to the correlation equation log k(20 degrees C) = s(N + E). With E parameters in the range of -10.4 to -13.9, the electrophilicities of 1a-e are comparable to those of analogously substituted benzylidenemalononitriles.     

2,2-dimethyl-5-(5-r-furfurylidene)-1,3-dioxane4,6 diones 7. Synthesis,structure, and properties of 2,2dimethyl-5-(3-furfuryldiene and 3-thienylidene)-1,3dioxane-4,6-diones

The corresponding 3 furfurylidene(thienylidene)-dioxanediones were obtained by the reaction of 2,5-R,Rfuran(thiophen)-3-carbaldehydes with Meldrum's acid. It was shown by x-ray crystallographic analysis that they have the s-trans disposition at the C₍₂₎=C₍₃₎ bond of the five-membered heterocycle and an exocyclic multiple bond. The character of the conjunction in their molecules was considered in the light of data of x-ray crystallographic analysis, electronic spectra, and NMR. The corresponding 3-furfuryl(thienyl)]dioxanediones were obtained by the selective ionic hydrogenation of the exocyclic double bond.For part 6 see [1]Kuban State Technological University, Krasnodar 350072. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 899–905, July, 1995. Original article submitted October 25, 1994; revision submitted June 5, 1995.     

无溶剂、无催化剂条件下5-[(3-吲哚基)-芳甲基]-2,2-二甲基- 1,3-二氧六环-4,6-二酮的合成

在无溶剂和催化剂条件下,由芳香醛、吲哚、丙二酸亚异丙酯的三组分缩合反应,制备了5-[(3-吲哚基)-芳甲基]-2,2-二甲基-1,3-二氧六环-4,6-二酮,产率为70%～85%,产物结构经1H NMR,IR确证.     

2,2-Dimethyl-5-(5-r-2-furfurylidene)-1,3-dioxane-4,6-diones

2,2-Dimethyl-5-(5-methyl-2-furfurylidene)-1,3-dioxane-4,6-dione crystals were subjected to an x-ray diffraction study. The unit cell of the crystal contains two symmetrically independent A and B molecules that exist in the x-cis conformation, which is stabilized by conjugation between the heteroring and, possibly, an intramolecular hydrogen bond.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1453–1456, November, 1988.     

5-[5-R-furfurylidene]-2,2-dimethyl-1,3-dioxane-4,6-diones 5. Nucleophilic replacement of halogen in the furan ring

Halogen in positions 3 and 5 of the furan ring in ftirfurylidenedioxanediones is readily replaced by dithiocarbonate, dithiocarbatnate, dithiophosphate, thiocyanate, and azide anions, and by thiourea, and secondary and tertiary amines. The conformation of the initial halogen derivative is retained in the substitution products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 327–334, March, 1994.     

5-[5-R-furfurylidene]-2,2-dimethyl-1,3-dioxane-4,6-diones 6. Synthesis,structure, and properties of substituted furylimino- and furfurylidenephosphoranes. Molecular and crystal structure of N-[5-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)methyl-2-furylimino(triphenyl)phosphorane

Furylimino- and furfurylidenephosphoranes have been synthesized by sequential conversions of 5-unsubstituted and 5-methylfurfut),Iidetiedio.yanediones. The ylide fragment linked directly with the furfurylidenedioxanedione residue displays strong electron-donating properties, as a result of which resonance occurs in the system of conjugated bonds. The molecular and crystal structure of the iminophosphorane was studied by x-ray structural analysis and the resonance of the bonds in the molecule was confirmed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 335–344, March, 1994.     

无溶剂、无催化剂条件下5-[(3-吲哚基)-芳甲基]-2,2-二甲基-l,3-二氧六环-4,6-二酮的合成

在无溶剂和催化剂条件下，由芳香醛、吲哚、丙二酸亚异丙酯的三组分缩合反 应，制备了5．[(3-吲哚基)-芳甲基]-2，2-二甲基-1，3-二氧六环-4，6-二酮，产 率为70％～85％，产物结构经～1H NMR，IR确证．     

Synthesis of 5-Aryl-2,2-dimethyl-4-oxaspiro[5,5]undecane-1,3-diones by Reformatsky Reaction

Alkyl 3-(1-bromocyclohexyl)-2,2-dimethyl-3-oxopropanoates react with zinc and aromatic aldehydes to yield 5-aryl-2,2-dimethyl-4-oxaspiro[5,5]undecane-1,3-diones.     

1,3-Dioxane-4,6-diones in organic synthesis (review)

Material dealing with methods for obtaining 1,3-dioxane-4,6-diones and their derivatives, methods for cleaving the 1,3-dioxane ring, and, within the framework of a synthone approach, trends in their utilization in organic synthesis is correlated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 579–599, May, 1991.     

Discovery and preliminary SAR of 5-arylidene-2,2-dimethyl-1,3-dioxane- 4,6-diones as platelet aggregation inhibitors

We herein document the discovery of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones as a novel family of platelet aggregation inhibitors. The preliminary optimization study enabled us to establish the most salient features of the structure-activity relationships in this series as well as to identify novel derivatives that are upto 60 times more potent than the hit structure 1 and slightly superior to the reference drug Milrinone.     

2,2-Dimethyl-5-(5-r-2-furfurylidene)-1,3-dioxan-4,6-diones. 1. Synthesis,properties, and structure

5-R-Furanaldehydes react with Meldrum's acid under Knoevenagel reaction conditions. The reaction products have s-cis conformation. The pK _a values of the electroneutral Lewis acids synthesized were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1325–1329, October, 1986.     

Photolysis of 5-diazo-2,2-dimethyl-4,6-dioxo-1,3-dioxane (diazoisopropylidenemalonic acid)

The principal pathway in the photochemical ( > 210 nm) transformation of 5-diazo-2,2-dimethyl-4,6-dioxo-1,3-dioxane in an aqueous medium (or in methanol) is splitting out of nitrogen and the Wolff rearrangement to give the stable 2,2-dimethyl-5-oxo-1,3-dioxolane-4-carboxylic acid (or its methyl ester), which undergoes decarboxylation only at temperatures above 150 ° C, whereas it undergoes hydrolysis to a hydroxymalonic acid in the presence of trifluoroacetic acid.Communication 6 from the series Chemistry of diazo dicarbonyl compounds. See [1] for Communication 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 321–325, March, 1985.     

Lactam and amide acetals. 52. Reaction of dimethylformamide diethylacetal with 2,2-dimethyl-4,6-dioxo-1,3-dioxane (Meldrum's acid)

Depending on the conditions of carrying out the reaction of dimethylformamide diethylacetal with the Meldrum's acid, either 2,2-dimethyl-4,6-dioxo-5-(N,N-dimethyl-aminomethylene)-1,3-dioxane or N,N,N¹N¹-tetramethylformamidinium salt of 2,2-dimethyl-4,6-dioxo-5-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-yl)methylene-1,3-di-oxane are formed. The two compounds can react with primary amines to form N-substituted 2,2-dimethyl-4.,6-dioxo-5-aminomethylene-1,3-dioxanes.For Communication 51, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 184–187, February, 1988.     

Synthesis and mechanism of formation of 5-benzylidene-2-thioxo-2,3-dihydro-(1H,5H)-pyrimidine-4,6-diones difluoromethoxy derivatives

Reactions of 5-benzylidene-2-thioxo-2,3-dihydro-(1H,5H)-pyrimidine-4,6-diones with a singlet difluorocarbene afford difluoromethoxy derivatives in 20–34% yield. The quantum-chemical analysis of the reaction mechanism showed that N,N-dimethylformamide is involved into the formation of difluoromethoxy derivatives.     

2,2-Dimethyl-5-(5-R-2-furfurylidene)-1,3-dioxane-4,6-diones. 4. Synthesis,stereostructures, and properties of thiophene analogs

The reaction of 2-formylthiophenes with Meldrum's acid gave the corresponding thenylidenedioxanediones, which, in contrast to the furfurylidene derivatives, have an s-trans conformation of the mutual orientation of the thiophene ring and the exocyclic double bond. Thenyldioxanediones were synthesized by the selective hydrogenation of the exocyclic double bond.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1338–1342, October, 1989.     

Simple,Safe, Large Scale Synthesis of 5-Arylmethyl-2,2-dimethyl-1,3-dioxane-4,6-diones and 3-Arylpropanoic Acids

Reaction of aryl aldehydes with Meldrum's acid 2 in the presence of formic acid and triethylamine gives 5-arylmethyl Meldrum's acid derivatives 4 at room temperature, whereas at 80–100°C 3-arylpropanoic acids 5 are formed.     

1,3-Dipolar cycloaddition of phthalazinium ylides to 5-arylidene-2-spirocyclohexane-1,3-dioxane-4,6-diones

Tetrahydrospiropyrrolo[2,1-a]phthalazines were synthesized by the reaction of 5-arylidene-2-spirocyclohexane-1,3-dioxane-4,6-diones with phthalazinium ylides. One of the reaction products, viz., 3-ethoxycarbonyl-2-(4-methoxyphenyl)-2′,2′-pentamethylene-1,2,3,10b-tetrahydrospiro[pyrrolo[2,1-a]phthalazine-1,5′-[1,3]dioxane]-4′,6′-dione, was studied by X-ray diffraction. The spectroscopic characteristics of the reaction products are discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2362–2365, October, 2005.