Studies on ketene and its derivatives. LXXXIII. Reaction of diketene with isoquinolinium and pyridinium methylide derivatives

Reaction of isoquinolinium bis(ethoxycarbonyl)methylide (I) with diketene gave diethyl 1-acetyl-2,3-dihydro-2-oxopyrrolo[2,1-α]isoquinoline-3,3-dicarboxylate (VI), which on hydrolysis with dilute hydrochloric acid afforded ethyl 1-acetyl-2-hydroxypyrrolo[2,1-α]isoquinoline-3-carboxylate (IX) and ethyl 3-methylpyrrolo[2,1-α]isoquinoline-3-carboxylate (X). On the other hand, isoquinolinium cyanoethoxycarbonylmethylide (IIa) reacted with diketene to give isoquinolinium cyano(3-ethoxycarbonyloxy-3-butenoyl)methylide (XIIIa) which was isomerized to isoquinolinium cyano(3-ethoxycarbonyloxy-2-butenoyl)methylide (XIII). Similarly, reactions of isoquinolinium cyanomethoxycarbonylmethylide (IIb) and pyridinium cyanoalkoxycarbonyl-methylide (IIIa,b) with diketene gave rise to the corresponding cyano(3-alkoxycarbonyloxy-3-butenoyl)methylides (XIIb, XVIa,b).     

Determination of YM992, a novel selective serotonin reuptake inhibitor, in rat and dog plasma by high-performance liquid chromatography with fluorescence detection

A high-performance liquid chromatographic method with fluorescence detection was developed for the determination of (S)-2-[[(7-fluoro-4-indanyl)oxy]methyl]morpholine monohydrochloride (YM992) in plasma. Plasma samples were extracted with n-hexane under alkali condition. After the organic solvent was evaporated to dryness, the residue was treated with 4-fluoro-7-nitrobezofurazan (NBD-F) in borate buffer (pH 7.5) at room temperature for 20 min. The reaction was terminated with hydrochloric acid and the resultant solution was injected onto HPLC without further purification. No interfering peak was observed at the retention time of YM992 or the internal standard. The calibration curve was linear with the concentration of YM992 up to 200 ng/ml. The limit of quantitation was 1 ng/ml. The intra- and inter-day relative standard deviation was less than 5.6% and 4.1%, respectively, and the intra- and inter-day relative error ranged from -3.0% to 17.2% and 2.8% to 7.5%, respectively. Using the assay, the plasma concentration of YM992 could be determined up to 8 and 10 h after the oral administration of YM992 to rats and dogs, respectively.     

Asymmetric electrochemical lactonization of diols on a chiral 1-azaspiro[5.5]undecane N-oxyl radical mediator-modified graphite felt electrode

A graphite felt electrode modified with (6S,7R,10R)-4-amino-2,2,7-trimethyl-10-isopropyl-1-azaspiro[5.5]undecane N-oxyl was prepared for electrocatalytic oxidation of diols; electrolysis of diols on the modified electrode yielded optically active lactones (92.0-96.4%), with an enantiopurity of 82-99% ee.     

Effect of terminal polar substituents on the nature of smectic A liquid crystals of a series of 4-(4'-octyloxybenzoyloxy)benzylidene-4'-substituted anilines

The nature of smectic A liquid crystals and the phase transitions from smectic A to nematic phases are studied in the homologous series of 4-(4'-octyloxy-benzoyloxy)benzylidene-4'-substituted anilines, in which the substituents are H, F, Cl, Br, I, NO₂ and CN. Measurements have been performed for the dipole moment of the molecule, the smectic A lattice period, the temperatures and the entropies of phase transitions, and the temperature dependence of the orientational order parameter, all of which provide information on the intermolecular pair potentials. It is shown that the introduction of a terminal polar substituent brings about counteracting contributions to the stability of the smectic A state. It is suggested that the reentrant nematic phase transition can appear in the strongly polar mesogens if the extent of antiparallel association of the molecules increases on lowering the temperature.     

A new synthesis of pyrimido[5,4-e]-as-triazine 4-oxides and their ring transformation to pyrrolo[3,2-d]pyrimidines

A new synthesis of certain pyrimido[5,4-e]-as-triazine 4-oxides and their ring transformation to pyrrolo-[3,2-d]pyrimidines by the 1,3-dipolar cycloaddition reaction is described. Thus, reaction of 6-hydrazino-1,3-dimethyluracil ( 1 ) with triethyl orthoformate gave 6-ethoxymethylenehydrazino-1,3-dimethyluracil ( 2 ). Treatment of 2 with arylamines gave 6-arylaminomethylenehydrazino-1,3-dimethyluracils ( 3a-e ). Nitrosative cyclization of 3a-e with sodium nitrite afforded 3-arylaminofervenulin 4-oxides ( 6a-e ). Reaction of 6a-e with acetylenic esters yielded 7-alkoxycarbonyl-6-arylamino-1,3-dimethylpyrrolo[3,2-d]pyrimidine-2,4(1H,3H-diones ( 15a-e and 16 ).     

Enrichment of trace amounts of aluminum using Chrome Azurol S and Chrome Azurol B for solid-state spectrophotometry

The composition of aluminum (III)-Chrome Azurol S (CAS) complex extracted on a membrane filter from solutions containing Zephiramine (Zeph) and perchlorate ions was estimated by determining the amount of CAS collected on the membrane filter together with the known amount of aluminum. The formation of a dimer with a ring structure, Al₂(CAS)₂(Zeph)₂ was postulated. With the use of Chrome Azurol B (CAB) in place of CAS, the resulting complex was much more strongly fixed on the membrane filter than the CAS complex. A quantitative recovery of aluminum as the CAB complex was attained even in the presence of 0.8M sodium perchlorate, which indicated that the CAB complex was highly hydrophobic.     

A new geometrical gravitational theory

A geometrical gravitational theory based on the connection ={ } + ln + ln –g ln is developed. The field equations for the new theory are uniquely determined apart from one unknown dimensionless parameter ₂. The geometry on which our theory is based is an extension of the Weyl geometry, and by the extension the gravitational coupling constant and the gravitational mass are made to be dynamical and geometrical. The fundamental geometrical objects in the theory are a metricg and two gauge scalars and. Physically the gravitational potential corresponds tog in the same way as in general relativity, the gravitational coupling constant to ^–2, and the gravitational mass tou(, ), which is a coscalar of power –1 algebraically made of and. The theory satisfies the weak equivalence principle, but breaks the strong one generally. We shall find outu(, )= on the assumption that the strong one keeps holding good at least for bosons of low spins. Thus we have the simple correspondence between the geometrical objects and the gravitational objects. Since the theory satisfies the weak one, the inertial mass is also dynamical and geometrical in the same way as is the gravitational mass. Moreover, the cosmological term in the theory is a coscalar of power –4 algebraically made of andu(, ), so it is dynamical, too. Finally we give spherically symmetric exact solutions. The permissible range of the unknown parameter ₂ is experimentally determined by applying the solutions to the solar system.     

Synthesis of novel organic oligomers containing Si?H bonds

Several organic oligomers (M_w = 10³–10⁴ order) containing Si?H bonds of the general formula 1 have been successfully synthesized by platinum-catalyzed partial hydrosilylation reaction of an allyloxy (or an allyl carbonate) end-blocked linear organic oligomer 2 with 2,4,6,8-tetramethylcyclotetrasiloxane, [CH₃(H)SiO]₄ ( 3 ) (hereafter called hydrocyclotetrasiloxane). ¹H-NMR spectroscopy confirmed the introduction of hydrocyclotetrasiloxane moiety into the oligomers through Si? C linkage by hydrosilylation reaction. ¹³C-NMR analysis revealed that the cyclic structure of the starting hydrocyclotetrasiloxane 3 was retained intact in product 1 . As the precursor for 1 , allyloxy (or allyl carbonate) end-blocked oligomers 2 could be prepared from hydroxyl-terminated oligomers 4 . The storage stability of product 1 was significantly influenced by the platinum catalyst still remaining in it. The poor stability was improved by decreasing the amount of the platinum catalyst and/or by adding coordinating compounds. As a result, an excellent stability of product 1 was obtained. © 1993 John Wiley & Sons, Inc.     

Anodic modification of proline derivatives using a lithium perchlorate/nitromethane electrolyte solution

[reaction: see text] N-Acyliminium cation of prolines was efficiently generated to accumulate in an undivided cell at 0 degrees C by an anodic oxidation of N-acylprolines or alpha'-phenylsulfanylated N-acylproline derivatives in a lithium perchlorate/nitromethane solution. The iminium cation intermediates gave modified prolines by a reaction with nucleophiles under mild conditions.