Synthesis of 2-(p-Toluenesulfonamido)-4-phenyl-4, 5-dihydro-1H-1, 3, 4-diazaphosphole 4-oxides

Some novel unsaturated five-membered organophosphorus heterocyclic compounds, 2-(p-toluenesulfonamido)-4-phenyl-4, 5-dihydro-1H-1, 3, 4-diazaphosphole 4-oxides 8 have been synthesized by Mannich-type reaction of p-toluenesulfonylguanidine with phenyldichlorophosphine and ketones.     

Synthesis and reactions of 3-iodo-4H-pyran-4-ones

3-Iodo-4H-pyran-4-ones have been synthesised in excellent yield by the reaction of acetylenic β-diketones with iodine monochloride and were converted into the corresponding 4H-pyran-4-thiones. The iodopyrones and thiopyrones gave with methylamine the respective N-methylpyridones and thiopyridones. The structure of the above compounds was confirmed from their spectral characteristics.     

Solution thermodynamics of first-row transition elements. 4. Apparent molal volumes of aqueous ZnSO4 and CuSO4 solutions from 15 to 55°C

The apparent molal volumes of ZnSO ₄ and CuSO ₄ have been determined from density data over the temperature range 15–55°C and concentration range 0–15 molal. The volume data have been fitted to the Pitzer formalism over the entire temperature and concentration range. The volume changes for the formation of ZnSO ₄ and CuSO ₄ ion pairs have been estimated over the temperature range covered and the partial molal volumes of ZnSO ₄ and CuSO ₄ ion pairs have been derived. The results were used to explain the hydration structure of the ion pair. UV spectral effects accompanying a change of temperature in the 15–65°C range in CuSO ₄ solution indicate direct coordination of sulfate anion to the cupric cation. The process is favored by an increase in temperature.     

Electronic structure of 4H-pyrido[1,2-a]pyrimidin-4-ones

The characteristic features of ir and uv spectra of 43 4H-pyrido[1,2-a]pyrimidin-4-one derivatives with electron donor or acceptor groups in position 3, and positions 6, 7, 8, or 9, respectively, have been systematically studied. On the basis of the spectra some conclusions have been drawn for the molecular structure. The negative solvent effect of the lowest-energy π → π* transition is investigated by the PPP method.     

Reaction of 4-methylene-5(4H)-oxazolones with diazomethane

The reaction of diazomethane with some (E) and (Z)-2-substituted-4-methylene-5(4)-oxazolones ( 1a-c ) under two different conditions, has been studied. (E) and (Z)-1,2-disubstituted-7-oxo-6-oxa-4-azaspiro[2.4]-hept-4-enes ( 3a-c, 4a-c ) were mainly obtained, together with multiple addition compounds. The reaction showed to be stereoselective only when the substituents were aromatic. Acid hydrolysis of compounds 3a and 4a produced a mixture of (E) and (Z)-3,5-disubstituted-tetrahydrofuran-2-ones ( 8a, 9a ). Smooth methanolysis of the ring led to (E) and (Z)-1-benzamido-cyclopropanecarboxylic esters ( 10a-c, 11a-c ), which, on acid hydrolysis, gave (E) and (Z)-1-amino-2-phenylcyclopropanecarboxylic acids 12a and 13a . The pmr spectra have been analyzed by an iterative computer method, and the computed best values obtained have been used to deduce the stereochemistry of the spiroderivatives.     

A Facile One-Pot Synthesis of 4-Acyl and 4-(1-Hydroxyethyl)Sydnones

A series of 4-formyl-, 4-acetyl- and 4-(l'-hydroxyethyl)sydnones have been prepared in good yields by reaction of sydnone with butyllithium or a Grignard reagent and N,N-dimethylformamide, N,N-dimethylacetamide and acetylaldehyde, respectively.     

Structural study of the smectic phases of several 4-cyanoalkoxybenzylidene-4'-alkylanilines

Abstract

A series of 4-cyanoalkoxybenzylidene-4'-alkylanilines (CN-nO. m; n = 3, 4, 6 and m = 4, 5, 8) have been synthesized. Their thermotropic liquid-crystalline polymorphism has been investigated using optical microscopy, differential scanning calorimetry and dilatometry. Nematic, smectic A and smectic B mesophases have been identified. The structure of the smectic phases has been studied with X-ray diffraction. Depending upon the compound and the temperature, the smectic layers have been found to be either single (A₁) or double (A₂) layers of molecules. Unexpected from a simple comparison with the well-known behaviour of the very similar nO. m smectogens, which belong to the class of the so-called symmetric and therefore exhibit single-layered smectics only, this structural behaviour has been interpreted to mean the importance of the dipole interactions of the terminal cyano groups. For CN-60.8, a transition has been detected at 64°C between the single and double layered structure.     

Photoionisation and fragmentation of the stereoisomers of 4-t-butylcyclohexyl acetate and 4-t-butylcyclohexyl methyl ether

The fragmentation of the stereoisomers of 4-t-butylcyclohexyl acetate and 4-t-butylcyclohexyl methyl ether has been studied by photoionisation mass spectrometry at 1216 Å and 584 Å. Deuterium substitution and high resolution mass spectrometry have been used to gain further insight into the fragmentation pathways.     

Electronic structures of the boron cage molecules B4H4, B4Cl4 and B4F4

Ab initio calculations have been performed on B₄H₄, B₄Cl₄ and B₄F₄ in order to aid our understanding of the bonding in these compounds, which is presumably based on a tetrahedral boron cage. This cage has only 8 electrons and so is less than that expected on the basis of the usual framework electron counting rules. Basis sets with polarisation functions were used at the SCF, CI and CPF levels of theory to confirm that the T _d structures are indeed more stable than the D _4h ones. Davidson-Roby population analyses were able to show that many factors, including 3-centre 2-electron bonding and backbonding from the ligand to the boron cage, are of importance in determining the relative stability of the three compounds, of which B₄Cl₄ is the only one that has yet been observed experimentally.     

First asymmetric synthesis of 3-alkoxycarbonyl-2-amino-4-aryl-4H-naphtho[1,2-b]pyrans

The first asymmetric synthesis of 3-alkoxycarbonyl-2-amino-4-aryl-4H-naphtho[1,2-b]pyrans, by Michael addition of 1-naphthol to chirally modified arylidenecyanoacetates 6 and 7 , is described. Good yields and low diastereomeric excesses have been obtained in the 1,4-conjugate additions. The absolute stereochemistry at C-4 in major isomers of pyrans 8 and 9 has been assigned as 5 by X-ray analysis of major pyran 8 .     

Stereocontrolled Syntheses of (4S, 5R)- and (4S, 5S)-Dihydroxy-N-Decanoic Acid-4-Lactones Via Biochemical Methods

(4S-5R)- and (4S-5S)-dihydroxy-n-decanoic acid-4-lactones have been synthesized in a stereocontrolled manner by a chemomicrobiological approach.     

Synthesis and Spectral Characterization of Some New 4-(2,6-Diarylpyridin-4-yl)-2H-chromen-2-ones

Some new 4-(2,6-diarylpyridin-4-yl)-2H-chromen-2-one derivatives 5a–l have been synthesized by reacting 4-(3-oxo-3-arylprop-1-enyl)-2H-chromen-2-ones 3a–c with appropriate 1-(2-oxo-2-arylethyl)pyridinium bromide salt 4a–d in the presence of ammonium acetate in refluxing glacial acetic acid. The newly synthesized compounds have been characterized by elemental and spectral analysis.     

Synthesis of 4-Cyano-4-dimethylamino-1,3-dimethyl-piperidines and 4-cyano-4-dimethyl-1,2,5-trimethyl-piperidines and investigation of features of their reactions with some nucleophilic reagents

4-Cyano-4-dimethylamino-1,3-dimethylpiperidines and 4-cyano-4-dimethylamino-1,2,5-trimethylpiperidines have been synthesized and the directions of their reactions with nucleophilic reagents (Grignard reagents, organolithium compounds, lithium tetrahydroaluminate, etc.) have been studied. Depending on the nature of the reagent, the reactions of the -amino nitriles take place by addition to the cyano group, by its replacement, or by these two directions simultaneously.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1224–1231, September, 1973.     

Synthesis and mesomorphic properties of n-alkyl 4-[4-(4-n-octyloxybenzyloxy-2,3,5,6-tetrafluorophenyl)ethynyl]benzoates

A new series of n-alkyl 4-[4-(4-n-octyloxybenzyloxy-2,3,5,6-tetrafluorophenyl)ethynyl)benzoates have been prepared. Polarizing microscopic textural observation shows that they are liquid crystals with nematic phase.     

Ab initio Calculation of the charge distribution and the ligand field splitting in the tetrahedral halo complexes CuCl 4 2− 4 and NiCl 4 2−

The charge distribution and the ligand field splitting in the tetrachloro complexes CuCl ₄ ^2– and NiCl ₄ ^2– have been investigated by means of the restricted Hartree-Fock method. A rather large basis set of contracted Gaussian type orbitals has been employed. The charge distributions have been analysed by means of Mulliken population analyses. The ligand field splitting 10Dq has been compared with literature results known for the octahedral cluster NiF ₆ ^4– occurring in KNiF₃. A detailed analysis has been carried out for CuCl ₄ ^2– . From calculations on a selected number of states of NiCl ₄ ^2– the Racah parameters B and C have been obtained.     

Synthesis of aldehyde and carboxylic acid derivatives from 2-hydroxymethyl-3-hydroxy-4H-pyran-4-one (α-hydroxymaltol)

α-Hydroxymaltol (2-hydroxymethyl-3-hydroxy-4H-pyran-4-one) ( 1 ) has been converted to the 3-O-methyl ether 2 and 3-O-p-nitrobenzyl ether 4 by standard methods. The ethers 2 and 4 have been oxidized by barium manganate to the corresponding aldehydes, 3 and 5 , in 91 and 77% yields respectively. Long-term reaction of 5 with hydrogen bromide in acetic acid gives 3-hydroxy-4H-pyran-4-one-2-carboxaldehyde ( 6 ). The aldehyde 3 is readily oxidized by short-term reaction with silver oxide to the corresponding acid 7 .     

19F NMR study ofcis- andtrans- effects of substituted triphenylphosphine ligands intrans-(4-fluorophenyl)triarylphosphine-tri(4-fluorophenyl)phosphineplatinum 4-fluorothiophenoxides

A number of compounds of the type oftrans-4-FC₆H₄Pt(PAr₃)₂SC₆H₄F-4, where Ar is a substituted phenyl group, have been prepared starting from the corresponding chlorides. By exchange reactions oftrans-4-FC₆H₄Pt[P(C₆H₄F-4)₃]₂SC₆H₄F-4 with the above-mentioned compounds or Ar₃P,trans-4-FC₆H₄Pt[P(C₆H₄F-4)₃][PAr₃]SC₆H₄F-4 have been generated in solution. For the latter compounds, the effect of Ar₃P oncis- andtrans-ligands has been studied by the¹⁹F NMR technique. It has been shown that thecis- andtrans-effects of Ar₃P run parallel and are well described by pK _a values and ionization potentials of the unshared electron pair in Ar₃P, as well as by ⁰ constants of the aryl groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1359–1363, July. 1995.     

Green approach for the synthesis of 4-coumarin-4H-pyrans from 4-formylcoumarins and their antibacterial study

A series of 4H-pyranocoumarin derivatives have been successfully synthesized under eco-friendly condition using triethylamine as a catalyst in short reaction time with excellent yield at room temperature. All the synthesized compounds were characterized by spectral analysis and screened for their antibacterial activity against Escherichia coli and Staphylococcus aureus, the results are quite promising.     

Reactions of some 4-methylene-4H-pyran derivatives with primary and secondary amines

4-Dicyanomethylene-4H-pyrans react with secondary amines to give 2-aminopyridine and 2-pyridone derivatives which, in turn, have been used to prepare copyrine derivatives. These pyrans and primary amines gave copyrine and iminopyridone derivatives in addition to the dicyanomethylene-1,4-dihydropyridines, which had been reported previously. Reaction of cyanocarbamoylmethylene-4H-pyrans with secondary amines gave 2-pyrones, and with primary amines, gave copyrines and 1,4-dihydropyridine derivatives.     

Alternative Strategies for the Fmoc Solid-Phase Synthesis of O4-Phospho-L-tyrosine-Containing Peptides

A number of biologically relevant O⁴-phospho-L-tyrosine-containing peptides have been synthesized by either the global phosphorylation of the side-chain-unprotected L-tyrosine moiety in presynthesized resin-bound peptides or alternatively by the incorporation of suitably protected O⁴-phospho-L-tyrosine building blocks in the continuous-flow method of Fmoc solid-phase peptide synthesis. Different phosphate-protecting groups have been applied.