Facile construction of substituted pyrimido[4,5-d] pyrimidones by transformation of enaminouracil

The reaction of 6-amino-1,3-dimethylpyrimidine-2,4[1H,3H]-dione [1] as a binucleophile with primary aromatic or heterocyclic amines and formaldehyde or aromatic [heterocyclic] aldehydes in a molar ratio [1:1:2] gave the pyrimido[4,5-d]pyrimidin-2,4-dione ring systems 2-5. Treatment of 1 with diamines and formalin in molar ratio [2:1:4] gave the bis-pyrimido[4,5-d]pyrimidin- 2,4-diones 6-8. Furthermore, substituted pyrimido[4,5-d]pyrimidin-2,4-diones with uracil derivative 11 or spiro indole 16 were synthesized. Synthesis of pyrimido[4,5-d]pyrimidin-2,4-diones with different substitution at C-5 and C-7 was achieved to give 13 and 18, respectively

Synthesis, characterization and RHFlab initio simulations of 2-amino-1,3,4-thiadiazole and its annulated ring junction pyrimidine derivatives

Michael addition reaction of the 2-amino-1,3,4-thiadiazole to chalcone as biselectrophile - afforded 5,7-diphenyl-6-[1,3-diphenylpropan-1-on-3-yl][l,3,4]thiadiazolo[3,2-[a]pyrimidine [3] instead of 5,7-diphenyl-5H-[l,3,4]thiadiazolo[3,2-a]pyrimidine [5] via further Michael addition at C[5] in pyrimidine moiety. The structure 3 was established through the aspect of ab initio calculations, elemental analysis and spectral data

use of polystyrene resin anchored carbohydrates as asymmetric media in grignard reaction with ketones

It has been demonstrated that chiral products can be formed in reactions between achiral Grignard reagents and aldehydes or ketones in optically active solvents or in a solvent that contains an optically active substance. Generally, the stereos electivity of such reactions is low. Inch et al have observed that in the presence of suitably substituted carbohydrate, e.g., 1,2 :5,6-di-O-isopropyUdeno-a-D-glucofuranose [I], Grignard-ketone [RMgBr - R'COR"] reactions can yield products with optical yields as high as 70 percent. On the other hand, he found that the Grignard-ketone reaction, C6H5MgBr -CH3COC2H5 in presence of the sugar derivative I, afforded the asymmetric carbinol, C6H5C[OH] [CH3]C2H5, with an optical yield of 10 percent. Accordingly, in this work we wish to report the Grignard-ketone reaction in the presence of a polymer anchored glucofuranose derivative II in order to improve the optical yield of the carbinol produced. The main reasons for using this polymer anchored sugar derivative II are the easy separation from the reaction medium and the possibility to use it for other reactions

Reduction of parochial ketones with optically active borohydride reagents

The phenomenon of asymmetric induction in the synthesis of compounds that already contain one or more asymmetric carbon atoms has been recognized for many years, the classic work in a cyclic system being that of McKenzie. Many types of asymmetric synthesis have been reported in which prochiral ketones have been reduced to optically active alcohols utilizing optically active reducing agents. Many studies mostly based on the use of lithium aluminium hydride [LAH] modified by chiral alcohols, amino alcohols and amines have been conducted altering both the reagents and the experimental conditions to obtain an optimum fit and to gain an insight into the mechanism of reduction. On the other hand, a few studies on the use of sodium borohydride [NaBH4] in the same type of asymmetric reduction have been reported. In the last few years, growing attention has been devoted to asymmetric synthesis under phase transfer condition. Recently, interesting results have been obtained by Sugimoto et al. in the asymmetric reduction of aromatic ketones with NaBH[4] in the presence of bovine serum albumin in alkaline solution. Accordingly, we were interested in the present investigations to study the asymmetric reduction of ketones with chirally modified reagents prepared from NaBH[4] and optically active acids

Reactivity of 3-cinnamoyl1-phenyl-2,4 [1H,3H] - quinoline-dione towards oxidation and oximation reactions Formation of fused heterocyclic quinolines

Acetyl-1,2,3,4-tetrahydro-2,4-dioxo-l-phenylquinoline [I] was condensed with benzaldehyde, crotonaldehyde and chloral hydrate to give he corresponding l-phenyl-3-substituted-2,4-[lH,3H]- quinolinediones [IIa-c]. Treatment of compound Ha with aniline gave 1-phenyl-3-[N-phenylcinnamoyl]-2,4 [lH,3H]-quinolinedione [IId]. In an alternative procedure compounds Ild-f were obtained via the condensation of anil, l-phenyl-3-[N- phenylcinnamoyl] 2,4-[lH,3H]-quinolinedione [IH]W, with the appropriate aldehyde namely, benzaldehyde, anisaldehyde and m-chlorobenzaldehyde to give l-phenyl-3-[N-substituted cinnamidoyl]-2,4 [lH,3H]-quinolinedione [Ild-f], respectively. The structure of compounds Ild-f was confirmed through their IR spectral data which showed bands at 3600-3300 [O H and N H] and at 1320 cm[-1][tert.-amine], besides their correct elemental analysis

Sodium borohydride reduction of propiophenone in presence of mixed sugar/acid media

Many chemists have attempted to prepare optically active compounds with chiral reagents, catalyst, and media. Of these investigations, the use of chirally modified metal hydrides to reduce prochiral ketones continues to be studied actively and high enantiomeric excesses of chiral carbinols have been achieved. Among metal hydrides, lithium aluminium hydride modified with chiral alcohols, amino alcohols, and amines has been mainly employed. Recently, attention has been paid however, to the use of sodium borohydricie [NaBH4] in asymmetric reduction. In the present work we would like to report an asymmetric reduction of propiophenone with modified reagents prepared from NaBH4 and d-camphoric acid [IV] in the presence of an optically active sugar derivative in THF solution, for the sake of improving the optical yields of chiral carbinols produced