Synthesis of 4,6-disubstituted pyrimidines via Suzuki and Kumada coupling reaction of 4,6-dichloropyrimidine

A series of 4,6-disubstituted pyrimidines were synthesized via Suzuki and Kumada coupling reaction of 4,6-dichloropyrimidine.     

A convenient two-step synthesis of 6-methylenesubstituted-4-trichloromethyl-2-methylsulfanyl pyrimidines

This work reports a two-step synthetic strategy to obtain a series of 6-methylenesubstituted-4-trichloromethyl-2-methylsulfanylpyrimidines from the cyclization of 5-bromo-4-methoxy-1,1,1-trichloro-pent-3-en-2-ones with 2-methyl-2-pseudothiourea sulfate, followed by nucleophilic substitution of 6-bromomethyl-4-trichloromethyl-2-methylsulfanylpyrimidine with a series of nucleophiles. Alternative strategies to obtain 6-halomethyl-4-trichloro[fluoro]methyl-2-methylsulfanyl pyrimidines have been addressed.     

The reaction of tetralones with nitriles: a simple approach to the synthesis of new substituted benzo[h]quinazolines, benzo[f]quinazolines and dibenzo[a,i]phenanthridines

The one-pot reaction of 1-tetralone with nitriles in the presence of triflic anhydride affords in good yields 2,4-disubstituted 5,6-dihydrobenzo[h]quinazolines, which oxidation with DDQ leads to the corresponding benzo[h]quinazolines. 2-Tetralone undergoes identical process forming 1,3-disubstituted 5,6-dihydrobenzo[f]quinazolines. However, when the reaction of 2-tetralone is carried out with methylthiocyanate as nitrile, 5-methylthiotetrahydrodibenzo[a,i]phenanthridines are isolated in good yields. Easy transformations of the methylthio group offer possible access to a variety of substituted dibenzo[a,i]phenanthridines.     

Synthesis and Transformation of Methyl 2‐(6‐Hydroxy‐2‐phenylpyrimidin‐4‐yl)acetate: Simple Preparation of Pyrimidines with Heterocyclic Substituents

A simple and efficient synthesis of four new substituted pyrimidines, compounds 9a – d , from the title compound 3 is described. Conversion of 3 to methyl (E)‐3‐(dimethylamino)‐2‐(6‐methoxy‐2‐phenylpyrimidin‐4‐yl)prop‐2‐enoate ( 4 ), followed by condensation with various dinucleophiles according to the ‘enaminone methodology’, afforded the target compounds 9 in medium‐to‐good yields.     

CRYSTAL AND MOLECULAR STRUCTURE OF THE SPIRODIPHOSPHITE ESTER 3,9-DIMETHOXY-2,4,8,10-TETRAOXA-3,9-DIPHOSPHASPIRO[5.5]UNDECANE

Abstract

The crystal and molecular structure of the strainless phosphite ester MeOP(OCH₂)₂C(CH₂O)₂POMe determined by x-ray means is reported. The methoxy groups are in axial positions on the chair-form-six-membered rings.     

Novel Synthesis of Condensed Pyridin-2(1H)-one and Pyrimidine Derivatives

The reaction of N-chloroacetyl derivatives 6-10 with morpholine yielded N-morpholin-1-yl acetyl derivatives 11-15 , which were subjected to Thorpe-Zieler cyclization with sodium tert -butoxide to produce the corresponding condensed pyridin-2(1H)-one derivatives 16-20 . Treatment of compounds 1 , 6-10 with either malononitrile or p -chlorobenzylidinemalononitrile in presence of triethylamine, afforded the corresponding pyrimidines 21-25 , 27 and pyridine derivative 26 respectively. Moreover compound 1 a was treated with ethyl isothiocyanoacetate to give the corresponding piprazine derivative 28 .     

Energetics of aminomethylpyrimidines: An examination of the aromaticity of nitrogen heteromonocyclic derivatives

The standard (p^o = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at the reference temperature of 298.15 K, of 2-amino-4-methylpyrimidine ((98.1 ± 1.6) kJ · mol⁻¹), 2-amino-4,6-dimethylpyrimidine ((55.9 ± 1.8) kJ · mol⁻¹) and 4-amino-2,6-dimethylpyrimidine ((60.1 ± 1.8) kJ · mol⁻¹) were calculated from the enthalpies of formation, in the crystalline phase, and enthalpies of sublimation, derived, respectively, from static bomb combustion calorimetry and Knudsen effusion technique results. In order to quantify the resonance effects arising from the substitution on the pyrimidine ring, hypothetical isodesmic reactions were used to analyze the experimental gaseous-phase enthalpies of formation. The aromaticity of benzene, pyridine, pyrimidine and the substituted pyrimidines was investigated in terms of magnetic (NICS), geometric (HOMA), electronic (Shannon aromaticity, QTAIMs ring critical point properties and HOMO–LUMO gap), reactive (hardness), vibrational (Kekulé mode) and spectroscopic (UV–Vis) properties.     

6-氯-N,N-二甲基嘧啶-4-胺的晶体结构研究

X-射线单晶衍射结果表明,所合成的6-氯-N,N-二甲基嘧啶-4-胺的晶体结构属正交晶系,Pbca空间群,晶胞参数为a=10.922(2),b=7.386(3),c=17.861(6)。由于在其晶格内存在着潜在的C—H…N和C—H…Cl两类分子间弱相互作用力,形成了二维网络结构,化合物变得更加稳定。     

β-Isothiocyanatoketones: A Convenient Source of Heterocyclic Compounds

Summary. The preparation of -isothiocyanatoketones and their reactions leading to formation of pyrimidine and bicyclic, tricyclic, tetracyclic, and pentacyclic heterocyclic compounds are reviewed. A few references concerning the rearrangement of heterocyclic compounds are also included. Some of the compounds reported have shown good antiinflammatory activity.     

2,4-Bis(methylsulfanyl)pyrimidine o-quinodimethane: a versatile building block for functionalized fused pyrimidines

Two alternative methods for the preparation of new pyrimidine Diels-Alder cycloadducts from the readily available 2,4-bis(methylsulfanyl)-5,6-dihydrocyclobuta[d]pyrimidine are presented. In the first method, the in situ generated pyrimidine ortho-quinodimethane reacts with various dienophiles to form the respective cycloadducts bearing two methylthio groups, which can be easily replaced by other functional groups. In the second method, one or both of the methylsulfanyl groups of the starting pyrimidine are replaced first and the resulting functionalized pyrimidines are able to undergo Diels-Alder cyclization with different dienophiles to form pyrimidine cycloadducts. These alternative synthetic strategies provide access to a wide variety of pyrimidine cycloadducts with a different substitution pattern on the pyrimidine ring. Yield data indicate that the electronic nature of the functional groups strongly influence the efficiency of the cycloaddition reaction.