Investigation of the Nucleophilic Rearrangement of 2-(Cyanomethyl)-1,4,6-trimethylpyrimidinium Iodide Into 4,6-Dimethyl-2-methylaminonicotinic Acid Nitrile

2-(Cyanomethyl)-1,4,6-trimethylpyrimidinium iodide is rearranged into 4,6-dimethyl-2-methylaminonicotinic acid nitrile by interaction with alcoholic solutions of sodium ethylate, methylamine, and also glycine and -alanine ethyl esters. This conversion was also observed for the first time for pyrimidinium salts during the process of recording ¹H NMR spectra in CD₃OD solution containing CD₃ONa. After the rearrangement deuterium exchange of the protons of the pyridine ring methyl groups was noted spectrally. It was demonstrated experimentally that for carrying out and completing the recyclization a quantity of nucleophilic reagent must convert the molar equivalent quantity of pyridinium salt.     

Rearrangement of O-vinyl-α-(amino-carbonyl)acetamidoximes to 2-aminopyrroles and 2-pyrrolinones

Rearrangement and cyclization of O-vinyl-α-(aminocarbonyl)acetamidoximes gives two isomeric 2-aminopyrroles and/or 2-pyrrolinones and this depends on the rearrangement route. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1328–1334, September, 2007.     

Preparation of 2-Alkyl- and 2-Acylpropenals from 5-(Trifluoromethanesulfonyloxy)-4H-1,3-dioxin: A Versatile Acrolein α-Cation Synthon

5-(Trifluoromethanesulfonyloxy)-4H-1,3-dioxin (3) participates in a variety of nucleophilic substitution reactions with cuprate reagents or in palladium catalyzed cross-coupling reactions to provide 5-substituted-4H-1,3-dioxins 5. Upon thermolysis, these compounds undergo facile retrocycloaddition reactions to generate the corresponding 2-substituted acroleins which, if necessary, can be trapped in situ with dienes or heterodienophiles. In particular, the heretofore unknown 2-acylacroleins can be generated using this methodology and trapped with enol ethers to afford 5-acyl-3,4-dihydro-2H-pyrans (6g,h), a substructural unit common to many natural products.     

Mass spectra of new groups of functionalized heterocycles. 4. 1-Alkyl-2-(alkylthio)pyrroles

The electron impact-induced fragmentation of 1-alkyl-2-(alkylthio)pyrroles is accompanied by rearrangements of the molecular and fragment ions with ring expansion.     

Synthesis of Nicotinic Acid Derivatives by the Reaction of Salts of 1-Alkyl-4,6-dimethyl-2-pyrimidinylacetic Acid Esters with Amines

A study was carried out on the enamine rearrangement of iodoalkylates of the ethyl ester of 4,6-dimethyl-2-pyrimidinylacetic acid to give ethyl esters of 2-alkylamino-4,6-dimethylnicotinic acid, which proceeds upon the action of various amines. The reaction with amines containing an alkyl substituent different from that at the quaternized nitrogen atom of the pyrimidinium salt leads to the formation of products of rearrangement and transamination. In the presence of water, the rearrangement is accompanied by the formation of the ethyl ester of 1,2-dihydro-2-oxo-4,6-dimethylnicotinic acid.     

Short Synthesis of 1-(3-tert-Butyl-1-phenyl-1H-pyrazol-5-yl)-3-(5-(2-morpholinoethoxy)-2H-chromen-8-yl) Urea Derivatives

A short and efficient synthesis of 1-(3-tert-butyl-1-phenyl-1H-pyrazol-5-yl)-3-(5-(2-morpholinoethoxy)-2H-chromen-8-yl) urea derivatives (1a–c), a novel type of p38 MAPK inhibitors, is described. The Claisen thermal rearrangement of arylpropargyl ethers was employd as a key step to synthesize the chromene core. The solvent effect on the ratio of the resultant two isomers of Claisen thermal rearrangement, namely 2-methylbenzofuran and 2H-chromen, was also investigated.     

Synthesis and Crystal Structure of （Z）-1- （3-Fluorobenzyl）-5-（（3-fluorobenzylimino）（2-hydroxy-4-methoxyphenyl）methyl）pyridin-2（1H）-one

The title compound （Z）-1-（3-fluorobenzyl）-5-（（3-fluorobenzylimino）（2-hydroxy-4- methoxyphenyl）methyl）pyridin-2（1H）-one （C27H22F2N2O3,Mr = 460.47） was synthesized and crystallized. The crystal belongs to the triclinic system,space group P1 with a = 9.951（6）,b = 10.059（6）,c = 12.927（7）A,α = 109.828（7）,β = 102.304（7）,γ = 104.898（7）°,Z = 2,V = 1110.2（11）A^3,Dc =1.377 Mg/m^3,μ（MoKα） = 0.102 mm^-1,F（000） = 480,the final R = 0.0449 and Rw = 0.1250 for 4595 observed reflections （I 〉 2σ（I））. X-ray analysis reveals that both m-fluorobenzyl groups are diorientationally disordered because of the rotation of C–C single bond which was represented as F（1）,F（2） and F（1＇）,F（2＇）. The diorientational disorder was refined and gave the occupancies of 0.665（4） and 0.335（4） for F（1） and F（1＇）,0.631（3） and 0.369（3） for F（2） and F（2＇）. Hydrogen bonds existing in the cell link different components to stabilize the crystal structure. The active data proved that the title compound has good anti-HBV activity.     

5-(2’-羧乙基)-6-烷基-3,4-二氢吡喃酮的合成

吡喃酮是许多天然产物的结构单元,我们曾由4-异丁酰基庚二酸在过量醋酸酐及乙酰氯存在下回流得到7-氧代-8,8-二甲基-△~9-六氢香豆素.本文由二氰乙基-β-二酮进行酮解水解反应得到4-酰基庚二酸1_(a-c)。 在过量醋酸酐、乙酰氯存在下由1_a、1_c为底物进行反应没有得到双环的香豆素衍生物.其产物和单纯以乙酐为缩合剂时的产物2_a、2_c相同,产率分别为68％、63％。2_c可在硫酸铁催化     

Complexation of Ni (II) and Zn(II) ions by 3-(1-naphthyI)-2-mercaptopropenoic acid

The complexation equilibria between Ni(II) and Zn(II) metal ions with 3-(1-naphthyl)-2-mercaptopropenoic acid (H₂NMP) were studied by glass electrode potentiometry, at 25 °C and 1.0 mol·dm^–3 in NaClO₄ as constant ionic medium in 50% (v/v) water-ethanol solutions. Formation constants for the complexes Ni(NMP), Ni(NMP) ₂ ^2– , Zn(NMP) and Zn(NMP) ₂ ^2– , refined by the MINIGLASS program, are reported.     

Mass Spectrometric Fragmentation of 1-（Benzyloxycarbonyl）amino-2-alkyl/cycloalkyl Thioacetates： a Thioester Pyrolysis-type Rearrangement under Electron Impact Ionization

Many four- and six-membered ring rearrangements have been observed under mass spectrometric ionization conditions to date1-7. 1-(Benzyloxycarbonyl)amino-2-alkyl/ cycloalkyl thioacetates are key intermediates for the synthesis of 1-substituted and cyclic t…     

Synthesis and Properties of 2-Alkyl-1-(2-aminoethyl)pyrroles

3-Chloropropenyl alkyl ketones or 2-methoxy-3-chloropropyl alkyl ketones in reaction withethylenediamine furnish previously unknown 2-alkyl-1-(2-aminoethyl) pyrroles. Their reaction with 2'2'-dichlorodiethyl ether gave rise to 2-alkyl-1-(2-morpholinoethyl)pyrroles, with anhydrides ofdicarboxylic acids the corresponding amidoacids and imides of dicarboxylic acids were obtained.     

Rearrangement of 2-methyl-2,3-epoxypentane: a kinetic study

The kinetics of the rearrangement of 2-methyl-2,3-epoxypentane over ZnCl₂/pumice stone is reported. 2-Methyl-3-pentanone and 2,2-dimethylbutanal are formed in parallel reactions. The reaction scheme and kinetic equations best fitting the experimental data are given. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and thermal behavior of cis- and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-2-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene

The cothermolysis of benzoyl(tert-butyl)bis(trimethylsilyl)silane with 2,3-dimethylbutadiene in a sealed tube at 140 °C for 24 h afforded cis- and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-2-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene (2 and 3) in a ratio of approximately 1:1 in 66% combined yield. When cis-silacyclohex-4-ene 2 was heated in a sealed tube at 250 °C for 24 h, dyotropic ring contraction took place to give 1-[(tert-butyl)(trimethylsiloxy)(trimethylsilyl)silyl]-3,4-dimethyl-1-phenylcyclopent-3-ene (4), but not trans-2-tert-butyl-4,5-dimethyl-2-phenyl-1-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene (6). The thermolysis of trans-silacyclohex-4-ene 3 under the same conditions, however, afforded two products, 1-silyl-1-phenylcyclopent-3-ene 4 and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-1-(trimethylsiloxy)-2-(trimethylsilyl)-1-silacyclohex-4-ene (5). The theoretical calculations were carried out to characterize the transition states and other local minima, and to evaluate the activation energies for the dyotropic rearrangement of 2 to 4 and 6, and 3 to 4 and 5. The energy barriers between 2 and 4, between 3 and 4, and between 3 and 5 were evaluated to be 188, 191, 192 kJ mol⁻¹, respectively. The energy barrier between 2 and 6, however, was calculated to be 201 kJ mol⁻¹ or higher. These results are consistent with the experimental finding that the thermal isomerization of 2 affords only 4, but 3 produces both 4 and 5.     

Hydrogen-bonded supramolecular motifs in crystal structures of trimethoprim barbiturate monohydrate (I) and 2-amino-4,6-dimethylpyrimidinium barbiturate trihydrate (II)

In the present study, we report the crystal structures of two organic salts, namely 2,4-diamino-5-(3′,4′,5′-trimethoxybenzyl)pyrimidinium (TMP) barbiturate monohydrate (TMPBAR) (I), 2-amino-4,6-dimethylpyrimidinium (AMPY) barbiturate trihydrate (AMPYBAR) (II). In both complexes, one ring nitrogen of TMP and AMPY are protonated as a result of proton transfer from the−CH₂ group of barbituric acid. In compound (I), the TMP cation and barbiturate anion are paired through twoN−H···O and one N−H···N hydrogen bonds. This pair further self-organizes through N−H···O hydrogen bonds to generate an array of six hydrogen bonds. These arrays are further cross-linked by N−H···O hydrogen bonds forming a sheet-like structure. The water molecule is also embedded in the sheet via O−H···O and C−H···O hydrogen bonds, forming a rosette-like supramolecular motif. TMP cations are also bridged by alternating water molecules via C−H···O and O−H···N hydrogen bonds. In compound (II), the symmetrical barbiturate anions self-organize on both sides through N−H···O hydrogen bonds generating a supramolecular chain. These chains are cross-linked by the three water molecules. A pair of barbiturate anions and two water molecules constitute an array of four hydrogen bonds (DADA quadruple array). These arrays are cross-linked by another water molecule. 2-Amino-4,6-dimethylpyrimidine cations are paired through N−H···N hydrogen bonds. These pairs are bridged by three water molecules generating a supramolecular ribbon. The barbiturate chains and base pairs are arranged in an alternate manner via N−H···O and O−H···O hydrogen bonds to generate a 3-D network.