AuCl(3)-catalyzed benzannulation: synthesis of naphthyl ketone derivatives from o-alkynylbenzaldehydes with alkynes

The reaction of o-alkynylbenzaldehydes 1 and alkynes 2 in the presence of a catalytic amount of AuCl3 in (CH2Cl)2 at 80 degrees C gave naphthyl ketone products in high yields. The AuCl3-catalyzed formal [4 + 2] benzannulation proceeds most probably through the coordination of the triple bond of 1 to AuCl3, the formation of benzo[c]pyrylium auric ate complex via the nucleophilic addition of the carbonyl oxygen atom, the Diels-Alder addition of alkynes 2 to the auric ate complex, and subsequent bond rearrangement. Similarly, the AuCl3-catalyzed reactions of o-alkynylacetophenone and o-alkynylbenzophenone with phenylacetylene afforded the corresponding naphthyl ketone products in good yields.     

Polycyclic N-heterocyclic compounds. XLI. Synthesis of 4-substituted 6,7-dihydro-5H-pyrimido[5,4-d][1]benzazepines, 1,2,5,6-tetrahydro-4H-imidazo[1′,2′:1,6]pyrimido[5,4-d][1]benzazepines and their related compounds as a series of potential blood platelet aggregation inhibitors

As a series of polyheterocyclic compounds for exploitation as anti-platelet agents, tricyclic heterocyclic compounds, 4-substituted 6,7-dihydro-5H-pyrimido[5,4-d][1]benzazepines 3–6, 9, 12–14 , and 16–26 , having nitrogen, oxygen, or sulfur containing functional groups at the 4-position, were prepared. In addition, tetra-cyclic heterocyclic compounds, 3-methyl-1,2,5,6-tetrahydro-4H-imidazo[1′,2′:1,6]pyrimido[5,4-d][1]benzaze-pinium chloride ( 7 ), 1,2,5,6-tetrahydro-4H-imidazo[1′,2′:1,6]pyrimido[5,4-d][1]benzazepines 10a-e , 2,3,6,7-tetrahydro-1H 5H-pyrimido[1′,2′:1,6]pyrimido[5,4-d][1]benzazepine ( 11 ), and 1,2,5,6-tetrahydro-4H-thiazolo-[3′,2′:1,6]pyrimido[5,4-d][1]benzazepinium chloride ( 15 ) via ring closure of 4-(hydroxyalkylamino)- 6, 9a-e , and 3c , and 4-(2-hydroxyethylthio)-6,7-dihydro-5H-pyrimido[5,4-d][1]benzazepine ( 14 ) with phosphoryl chloride or thionyl chloride, respectively, were also prepared. Their inhibitory activities against collagen-induced aggregation of rabbit blood platelets in vitro were investigated. Among them, compound 5 having a morpholino group at the 4-position on the tricyclic nucleus, which enhanced the activity more than 14-fold as compared with aspirin, was found to have the most satisfactory in inhibitory activity.     

Propylene carbonate as a solvent for salting-out extraction and subsequent differential pulse polarography

Summary Selective and sensitive procedures are described for the direct differential pulse polarographic determination of antimony(III), indium(III) and cadmium(II) in propylene carbonate. This method was based on the salting-out extraction of their halide complexes into the solvent from acidic aqueous media. The extracted Sb(III), In(III) and Cd(II) complexes exhibit sharp differential pulse polarographic peaks at –0.21 V, –0.63 V and –0.72 V vs. SCE in salted-out propylene carbonate phases respectively. The lower limits of determination are 5.0g for Sb(III), 0.6g for In(III), and 0.2g for Cd(II) in 10 ml of the organic phase. A number of foreign ions are eliminated through both processes of solvent extraction and polarography using propylene carbonate.

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Propylencarbonat als Lösungsmittel für die Fällungs-Extraktion und die nachfolgende Differential-Puls-Polarographie

Zusammenfassung Selektive und empfindliche Verfahren für die direkte Bestimmung von Sb(III), In(III) und Cd(II) in Propylencarbonat mit Hilfe der Differential-Puls-Polarographie wurden beschrieben. Die vorliegende Methode beruht auf der Fällungs-Extraktion der Halogenid-Komplexe aus wäßrig-saurem Medium in das Lösungsmittel. Die extrahierten Komplexe des Sb(III), In(III) und Cd(II) ergeben scharfe Peaks bei –0,21 V, –0,63 V und –0,72 V gegen die Kalomelelektrode in den betreffenden Propylencarbonat-Phasen. Die unteren Grenzen der Bestimmungen liegen bei 5,0g Sb, 0,6g In bzw. 0,2g Cd in 10 ml organischer Phase. Eine Anzahl Fremdionen wird durch die beiden Prozesse der Extraktion und der Polarographie in Propylencarbonat ausgeschaltet.

     

Synthesis of 3-aminopyrazolo[3,4-d]pyrimidine derivatives using N-bis(methylthio)methylene-p-toluenesulfonamide

N-Bis(methylthio)methylene-p-toluenesulfonamide ( 1 ) reacted with active methylene compounds such as malononitrile ( 2a ) and, cyanoacetamide ( 2b ) to give the corresponding 3-methylthio-3-p-toluenesulfonylami-nopropenenitrile derivatives 3a,b which were found to be convenient starting materials for the synthesis of 3,5-diaminopyrazole derivatives. Reaction of 3a and 3b with hydrazines gave the corresponding 3,5-diaminopyrazoles 4a-e , key intermediates for the synthesis of 3-aminopyrazolo[3,4-d]pyrimidine derivatives 5a-d .     

Characterization of saccharide moiety in the electroplax sodium channel.

Carbohydrate chains on the large peptide of the voltage-sensitive sodium channel from Electrophorus electricus electroplax have been partially characterized by the lectin-blotting technique combined with digestion using three glucosidases: neuraminidase, endo-beta-N-acetylglucosaminidase H, and peptide: N-glycosidase F. The results show that both N-linked oligosaccharides and O-linked (mucin-type) oligosaccharides are present. In N-linked oligosaccharides, the results suggest the presence of complex- and hybrid-type oligosaccharides which contain bisecting N-acetylglucosamine(s), as well as the complex-type oligosaccharides with the alpha-Fuc-GlcNAc-(Asn) residue(s). In O-linked oligosaccharides, they must carry Gal beta1----3GalNAc- moieties which contain NeuNAc residues in the terminal.     

Chirality exchange from sp3 central chirality to axial chirality: benzannulation of optically active diaryl-2,2-dichlorocyclopropylmethanols to axially chiral alpha-arylnaphthalenes

Chirality exchange benzannulation of optically active (1S)-aryl(aryl')-2,2-dichlorocyclopropylmethanols (>99% ee) using TiCl4 successfully proceeded to give axially chiral (M)-alpha-arylnaphthalenes with excellent levels of stereo induction (>99% ee). This unique transformation involves the single-step chirality exchange from sp3 central chirality to axial chirality, that is, a type of excellent memory effect.     

Palladium-catalyzed hydrocarbonation of methyleneaziridines with carbon pronucleophiles

The reaction of methyleneaziridine 1 with carbon pronucleophiles (2, H-CR₃) proceeds smoothly in the presence of a palladium catalyst affording the corresponding hydrocarbonation products 5 in good to high yield.     

Benzyne-induced ring opening reaction of thiiranes. Efficient synthesis of phenyl vinyl sulfides

A series of thiiranes react with benzyne to provide an efficient synthesis of phenyl vinyl sulfides. The reaction is stereospecific, thus producing cis-(phenylthio)-stilbene from cis-2,3-diphenylthiirane and trans-(phenylthio)stilbene from trans-2,3-diphenylthiirane.