Grignard reaction 0f 2-phenyl-tetrahydropyrrolo-1,5,2-oxazaphospholes,observation of the stereospecific inversion of configuration

Grignard reaction of bicyclic oxazaphospholes proceeded with inversion of configuration to provide chiral phosphinic esters of known absolute configurations.     

Stoichiometry and conformation of the azacrown moiety in sodium complexes of azacrown ethers. A Raman/IR spectroscopic study. Part II: Complexes of 4,13-diaza-15-crown-5

4,13-Diaza-15-crown-5 and three of its sodium complexes (bromide, iodide and thiocyanate) were studied using Raman and IR spectroscopy and normal coordinate calculations, following the corresponding study on the sodium complexes of 4,13-diaza-18-crown-6 in the preceding paper. Complex formation was again accompanied by a characteristic shift of the bands, especially of those in the 800–900 cm^–1 region. The complexes of 4-13-diaza-15-crown-5 were distinct from those of 4-13-diaza-18-crown-6, in that both of the bands at 830 and 890 cm^–1 of the parent azacrown were affected on complex formation and in that only the 11 complex was formed. Normal mode calculations were made to predict conformations of the azacrown ring of the parent 4,13-diaza-15-crown-5 and its sodium complexes. Attention was paid to the different extent of mismatch in size of a sodium ion and azacrown cavities.     

Construction of molecular wires based on a gold(I) bis-sigma-acetylide building block incorporated into ruthenium(II) polypyridyl complexes

An Ru(II)-Au(I)-Ru(II) triad has been synthesized from [Ru(bpy)2(3-ethynylphenanthroline)]2+ with Au(tht)Cl and characterized by spectroscopic means such as NMR and ESI-MS; the Ru(II)-Au(I)-Ru(II) triad shows an intense emission at 620 nm upon excitation at 360 nm, which suggests an efficient energy transfer from the Au site to Ru sites via extended pi-conjugation through the ethynyl units.     

Selective N-Monoalkylation of aniline derivatives by use of alkali cation exchanged X- and Y-type zeolites

Alkali cation exchanged X- and Y-type zeolites are employed to promote the reactions of aniline derivatives with alkylating agents in organic solvent. The N-alkylation is accelerated by the cooperative function of the acid and base sites on the potassium cation exchanged X- and Y-type zeolites to give the N-monoalkylated product in very high selectivity. Especially the use of the zeolite is found to be effective for N-alkylation of deactivated aromatic amines like nitroaniline. The highly selective N-monoalkylation is attributed to the reaction occurring inside the homogeneous narrow cavities of zeolites.     

Aqueous solutions of sodium methylsulfate by Raman scattering,NMR, ultrasound,and density measurements

Dynamic properties of sodium methylsulfate were investigated by means of NMR and Raman spectroscopies. The concentration dependence of the spin-lattice relaxation times of²³Na in aqueous solutions of sodium methylsulfate show no detectable specific interactions between sodium and methylsulfate ions. Raman band profiles of the S-O stretching mode of methylsulfate ion in aqueous solution show asymmetry above about 3.0 mol-dm^–3. Furthermore, the proton spin-lattice relaxation rates of the methylsulfate ion in D₂O increase linearly up to about 3.0 mol-dm^–3, but above this concentration they deviate from linearity.These experimental results indicate that dynamic properties of methylsulfate ion are affected by ion-water interactions. Raman band asymmetry is attributed to the non-uniformity of the distribution of water molecules around the methylsulfate ion. This interpretation is supported by the theory developed by Knapp and Fischer. The distortion of the distribution of water molecules around ions is also discussed on the basis of the overlap of the hydration layer around methylsulfate ion which is estimated by the measurement of sound velocity and density.     

Selective reduction of NOX with C3H6 over Cu incorporated into silicoalumino-phosphate (SAPO)

Cu ion-exchanged SAPO-34 which is a highly active catalyst for selective reduction of NO with C₃H₆, was synthesized and the Cu ion was characterized in the SAPO-34 by ESR, XPS, IR, and XAFS. ESR study indicated that two kinds of Cu(II) with different environments exist in SAPO-34. The Cu(II) species disappeared immediately by C₃H₆ treatment and recovered by oxygen treatment. XAFS study indicated that most of the Cu(II) was reduced to Cu(I) under the presence of C₃H₆. These studies revealed that a selective NO reduction by C₃H₆ over SAPO-34 should proceed by the redox reaction of a copper ion between Cu(I) and Cu(II).     

Photocatalytic redox-neutral hydroxyalkylation of N-heteroaromatics with aldehydes

Hydroxyalkylation of N-heteroaromatics with aldehydes was achieved using a binary hybrid catalyst system comprising an acridinium photoredox catalyst and a thiophosphoric acid organocatalyst. The reaction proceeded through the following sequence: (1) photoredox-catalyzed single-electron oxidation of a thiophosphoric acid catalyst to generate a thiyl radical, (2) cleavage of the formyl C–H bond of the aldehyde substrates by a thiyl radical acting as a hydrogen atom transfer catalyst to generate acyl radicals, (3) Minisci-type addition of the resulting acyl radicals to N-heteroaromatics, and (4) a spin-center shift, photoredox-catalyzed single-electron reduction, and protonation to produce secondary alcohol products. This metal-free hybrid catalysis proceeded under mild conditions for a wide range of substrates, including isoquinolines, quinolines, and pyridines as N-heteroaromatics, as well as both aromatic and aliphatic aldehydes, and tolerated various functional groups. The reaction was applicable to late-stage derivatization of drugs and their leads.

Hydroxyalkylation of N-heteroaromatics with aldehydes was achieved using a binary hybrid catalyst system comprising an acridinium photoredox catalyst and a thiophosphoric acid organocatalyst.     

Synthesis and Synthetic Application of Phosphonoketene Dithioacetals. New Synthesis of Dithioallenes and (alpha-Dithiocarboxyvinyl)phosphonates

Phosphonoketene dithioacetals 3a-e were obtained in good yields by the reaction of ethyl phosphonoacetates 1a,b with 2-4 equiv of thiols 2a-c in the presence of an alkylaluminum dichloride or dialkylaluminum chlorides. Reaction of 2,2-dithio-1-phosphonovinyl anions with aldehydes afforded allylic alcohols 4-7, 11-18 in good to moderate yields. Treatment of the alcohols 4-6 with t-BuOK in THF led to symmetrical [2 + 2] cycloadducts 20-22 of 1,1-(ethylenedithio)allenes in moderate yields, while a similar reaction of the alcohols 11-13 produced a mixture of symmetrical and unsymmetrical [2 + 2] cycloadducts of 1,1-(trimethylenedithio)allenes,23a-25a and 23b-25b, in 55-94% yields. The alcohol 15 on a similar treatment gave 3-tert-butyl-1,1-bis(ethylthio)allene (26) in quantitative yield. The structures of 20 and 23b were determined by X-ray analysis. Treatment of the alcohols 15 and 18 with trifluoromethanesulfonic acid/n-Bu(4)NX (X = Br, I) or triphenylphosphine/CBr(4) in CH(2)Cl(2) afforded alpha-phosphonodithioacryclic acid esters 34 and 35 in 25-52% yields. The tandem Michael-Wittig reaction of 35 with sodium salt of 2-pyrrolecarbaldehyde in DMF gave ethyl 3-phenyl-3H-cyclopenta[a]pyrrole-2-dithiocarboxylate (36) in 25% yield.     

Sedimentation potential of complexes of nitroamminecobalt(III) in aqueous solution at 25°C

Sedimentation potentials (SP) were measured for a series of nitroamminecobalt(III) chlorides in aqueous solution. The magnitudes of the sedimentation potentials varied with the number of NO ₂ ^– ligands in the complexes and a definite positive signal was observed for a neutral complex [Co(NO₂)₃(NH₃)₃]⁰. The division of the partial molar volumes of nitroamminecobalt(III) complexes based on the observed SP values resulted in comparable values of the partial molar volume for the Cl^– ion, suggesting no appreciable hydrolysis nor ionic association occur for these nitroammine-cobalt(III) complexes.