Addition of esters of nitroacetic acid to α,β-unsaturated ketones

Summary The addition reaction of esters of nitroacetic acid to, -unsaturated ketones was studied, and new esters of ketonitroacids were prepared.     

Cyclic seleninate esters as catalysts for the oxidation of sulfides to sulfoxides, epoxidation of alkenes, and conversion of enamines to α-hydroxyketones

Cyclic seleninate esters serve as catalysts for the rapid oxidation of sulfides to sulfoxides, alkenes to epoxides, and enamines to α-hydroxyketones. Optimal conditions were found that minimize the overoxidation of the product sulfoxides to sulfones and the hydrolysis of epoxides to diols. In some examples such as styrene derivatives, oxidative cleavage was observed instead of epoxidation. The enamine oxidations proceed via the initial formation of dimeric 2,5-diamino-1,4-dioxane species, which were hydrolyzed in situ to the final products. The structure of one such dimer was confirmed by X-ray crystallography.     

Thermodynamics of protonation of AMP,ADP, and ATP from 50 to 125°C

The interaction of adenosine 5-monophosphate (AMP), adenosine 5-diphosphate (ADP), and adenosine 5-triphosphate (ATP) ions with protons in aqueous solution has been studied calorimetrically from 50 to 125°C and 1.52 MPa. At each temperature, the reaction of acidic AMP with tetramethylammonium hydroxide was combined with the heat of ionization for water to obtain the enthalpy of protonation of AMP, while the reactions of HCl with deprotonated tetramethylammonium salts of ADP and ATP were used to obtain the enthalpies of protonation of ADP and ATP. Equilibrium constant K, enthalpy change H^o, entropy change S^o, and heat capacity change C _p ^o values were calculated for the stepwise protonation reactions as a function of temperature. The reactions involving the first protonation of AMP, ADP, and ATP and the third protonation of ADP and ATP were endothermic over the temperature range studied, while that involving the second protonation is exothermic for AMP and ADP, but is exothermic below 100°C and endothermic at 125°C in the case of ATP. Consequently, log K values for the first and third protonation reactions (phosphate groups) increase while those for the second protonation reaction (N₁-adenine) decrease in the cases of AMP and ADP and go through a minimum in the case of ATP as temperature increases. The H^o values for all protonation reactions increase with temperature. The magnitude and the trend for the H^o, S^o, and C _p ^o values with temperature are discussed in terms of solvent-solute interactions. The magnitude of the C _p ^o values for the second protonation is consistent with little interaction between the phosphate ion and the protonated N₁ site of the adenine moiety in AMP, but indicates moderate interaction between these groups in ADP, and strong interaction in ATP.     

Addition of Organosamarium Reagents toα, β-Unsaturated Esters

Compared to the extensive use of samarium diiodide in organic synthesis', little reportsappeared on the application of samarium metal in organic synthesis. As early as 1971Evans and co-workers had prepared phenylsamarium iodide from iodo-benzene andsamarium metal'. But they found that samarium is not so active as ytterbium. In 1986Fukuzawa also prepared the organosamarium intermediate similar to Grignard reagent'.It was Curran who firstly proved and named the samarium Grignard reaction in 19…     

Gold-catalyzed Synthesis of Pyridine Containing Macrocycles, Related to Porphyrin

Porphyrins are very important substances used in a wide range of model systems in many areas, such as biomimic chemistry and material science. This kind of macrocycle generally consists of 5-membered ring to form a cyclic extended aromatic network. Recently much work have been done concerning the modification of porphyrins core structures, and many kinds of analogues have been recorded. One of the important aspects was the research of the porphyrinogen ligand.These macrocycles bear functional resemblance to certain kind of polydentate ligand, and provide a variety of tri-dimensional binding cavities for metal ions. In addition, some other kinds of analogues have been recorded, involving the introduction of a CH unit to replace one of the nitrogen atoms. We also notice the fact that pyridine is a very effective ligand, and it can coordinate with many kinds of metals. Based on these observations, we would like to design and synthesize a new porphyrinogen (5) analogue containing a NNNN core, two of the N atoms from pyrrole and the other two N from pyridine. Such core modifications may alter the electronic structure of the ring and provide variable cavity for metal coordination.     

Conjugate Addition of Alkyllithium Reagents to α,β-Unsaturated N,N',N'-Trimethylhydrazides

The site of nucleophilic attack by an alkyllithium reagent upon an α,β-unsaturated carbonyl compound is governed by, among other factors, the nature of the group attached to the carbonyl.¹ Thus the amount of carbonyl addition decreases in favor of conjugate addition for the α,β-unsaturated series: aldehyde, ketone, ester, amide. We wish to report that α,β-unsaturated carboxylic acid trimethylhydrazides, which have an exceptionally unreactive carbonyl group², undergo exclusive conjugate addition with simple alkyllithium reagents.³ Furthermore, the derived hydrazide lithium enolates can be transformed in convenient and useful ways.     

Four‐Component Cyclocondensation of Aminodiazines,Glyoxal, Formaldehyde,and Methanol to Imidazolidines

Four‐component reaction of aminodiazines (2‐aminopyrimidine and 2‐aminopyrazine), glyoxal, formaldehyde, and methanol yields trans‐4,5‐dimetoxy‐1,3‐bis(2‐pyrimidinyl)imidazolidine (5a) and trans‐4,5‐dimetoxy‐1,3‐bis(2‐pyrazinyl)imidazolidine (5b), respectively. Changing methanol to acetonitrile leads to the formation of the corresponding 1,3‐bis(2‐pyrimidinyl) and‐1,3‐bis(2‐pyrazinyl)‐ derivatives of trans‐4,5‐dihydroxyimidazolidine (6). Details of the proposed mechanism are discussed.     

Access to β,γ-diamino acids. Application to the synthesis of 3-deoxyaminostatine

The synthesis of orthogonally protected diastereo- and enantiopure β,γ-diamino acids starting from natural α-amino acids is described, as well as its application to the synthesis of fully protected 3-deoxyaminostatine.     

From Monomers to π Stacks, from Nonconductive to Conductive: Syntheses, Characterization, and Crystal Structures of Benzidine Radical Cations

Salts that contain radical cations of benzidine (BZ), 3,3',5,5'-tetramethylbenzidine (TMB), 2,2',6,6'-tetraisopropylbenzidine (TPB), and 4,4'-terphenyldiamine (DATP) have been isolated with weakly coordinating anions [Al(OR(F) )(4) ](-) (OR(F) =OC(CF(3) )(3) ) or SbF(6) (-) . They were prepared by reaction of the respective silver(I) salts with stoichiometric amounts of benzidine or its alkyl-substituted derivatives in CH(2) Cl(2) . The salts were characterized by UV absorption and EPR spectroscopy as well as by their single-crystal X-ray structures. Variable-temperature UV/Vis absorption spectra of BZ(.) (+) [Al(OR(F) )(4) ](-) and TMB(.) (+) [Al(OR(F) )(4) ](-) in acetonitrile indicate an equilibrium between monomeric free radical cations and a radical-cation dimer. In contrast, the absorption spectrum of TPB(.) (+) SbF(6) (-) in acetonitrile indicates that the oxidation of TPB only resulted in a monomeric radical cation. Single-crystal X-ray diffraction studies show that in the solid state BZ and its methylation derivative (TMB) form radical-cation π dimers upon oxidation, whereas that modified with isopropyl groups (TPB) becomes a monomeric free radical cation. By increasing the chain length, π stacks of π dimers are obtained for the radical cation of DATP. The single-crystal conductivity measurements show that monomerized or π-dimerized radicals (BZ(.) (+) , TMB(.) (+) , and TPB(.) (+) ) are nonconductive, whereas the π-stacked radical (DATP(.) (+) ) is conductive. A conduction mechanism between chains through π stacks is proposed.     

Micelle to vesicle transitions of N-dodecyl-1, ω-diaminoalkanes: effects of pH, temperature and salt

The self-assembly behavior of pH-sensitive amphiphiles N-dodecyl-1, 2-diaminoethane (C12N2N), N-dodecyl-1, 3-diaminopropane (C12N3N) and N-dodecyl-1, 4-diaminobutane (C12N4N) has been studied in aqueous solutions. Light scattering, viscosity and cryo-transmission electronic microscopy (cryo-TEM) results revealed that the aggregates transferred from spherical micelles to vesicles (MVT) via wormlike micelles as the pH was gradually varied from acidic to basic conditions. pH-dependent zeta potential and (1)H NMR studies confirmed these transitions. Interestingly, the formed wormlike micelles could transform into vesicles upon heating, which was studied by cryo-TEM, light scattering and viscosity techniques in detail. It is concluded that the pH and thermal MVT are a general phenomenon in all three amphiphiles investigated. Furthermore, NaCl induced a wormlike micelle to vesicle transition was also observed in C12N2N solution.     

Addition of α,α-dichloropropionitrile to unsaturated compounds under conditions of metallocomplex initiation

,-Dichloropropionitrile reacts with unsaturated compounds in the presence of complex initiating systems based on metal carbonyls. The systems based on iron pentacarbonyl are the most efficient.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1595–1596, August, 1995.The work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-04497).     

Stereoselective Addition of N-Alkylhydroxylamines to α,β-Unsaturated Nitro Compounds

Since Baldwin reported that the addition of N-substituted hydroxylamines to α,β-un- saturated ester is a general procedure for the synthesis of isoxazolidin-5-ones1, the conjugate addition of N-alkylhydroxylamines to α,β-unsatutated esters2-4, lactone…     

Organocatalytic oxy-Michael addition of alcohols to α,β-unsaturated aldehydes

1,4-Addition of alcohols to α,β-unsaturated aldehydes was found to be efficiently promoted by biphenyldiamine-based catalyst 3 without formation of the acetals.     

1,4-Addition of tetraethyl fluoromethylenebisphosphonate to α,β-unsaturated compounds

Tetraethyl fluoromethylenebisphosphonate in the presence of cesium carbonate in DMF undergoes efficient 1,4-addition to Michael acceptors having terminal double bond such as α,β-unsaturated ketones, esters, sulfones, sulfoxides, and phosphonates to yield the corresponding adducts (α-alkyl-α-fluoromethylenebisphosphonates) in good to excellent yields.     

Palladium-catalyzed 1,4-addition of diarylphosphines to α,β-unsaturated N-acylpyrroles

Highly stereoselective asymmetric 1,4-addition of diarylphosphines to α,β-unsaturated N-acylpyrroles catalyzed by a PCP pincer-Pd complex has been developed for the synthesis of chiral phosphines with excellent stereoselectivity (91-99% ee) under mild conditions. The products obtained can be further converted into chiral phosphine-oxazoline ligands.     

Palladium-catalyzed 1,4-addition of diarylphosphines to α,β-unsaturated aldehydes

A highly stereoselective asymmetric 1,4-addition of diarylphosphines to α,β-unsaturated aldehydes catalyzed by a bis(phosphine) pincer-Pd complex has been developed for the synthesis of chiral phosphines with excellent stereoselectivity (up to 98% ee) under mild conditions. The application of the current method to the synthesis of enantiopure bisphosphine and its pincer-Pd complex has also been demonstrated.