Yuji Takikawa

Novel synthesis of 1,3,5-triselenanes from aldehydes, and novel generation of selenoaldehydes by fragmentation of 1,3,5-triselenanes

Abstract Reaction of aldehydes with (Me 3 Si) 2 Se in the presence of Lewis acid afforded 1,3,5-triselenanes via selenoaldehydes. Novel and convenient generation of selenoaldehydes was also achieved by thermally- or Lewis acid-induced fragmentation of 1,3,5-triselenanes.

Effects of molecular structure of aliphatic diols and polyalkylene glycol as lubricants on the wear of aluminum

Abstract The lubrication characteristics of aliphatic diols and polyalkylene glycol on the aluminum-steel friction surface were investigated by using a FALEX machine. Aluminum wear is not influenced by the viscosity of diol and polyalkylene glycol, but the molecular structure dose have a significant effect. The lubricant compounds having OH groups on both ends of molecule increased aluminum wear but the wear substantially decreased when OH groups were etherificated with alkyl groups. Wear also decreased when alkyl group(s) was added to the diol. The nascent aluminum surface reacts with alcohol to partially form aluminum alkoxide. As a result, the oxidation layer declines, and wear increases. Furthermore, the wear of aluminum is increased by such a molecular structure that makes it difficult for an anti-wear layer to form on the friction surface.

REACTION OF 4-CHLORONITROBENZENE WITH ELEMENTAL SULFUR IN LIQUID AMMONIA

Abstract An interesting compound, 4-nitrobenzenethiosulfenamide (2) was isolated in the reaction of 4-chloronitrobenzene (1) with elemental sulfur in liquid ammonia at about 20°C. This compound yielded 4-nitrobenzenethiol (3), 4-nitroaniline (4), 4,4′-dinitrodiphenyl disulfide (5) and 4,4′-dinitrodiphenyl sulfide (6) upon further reaction in liquid ammonia. When elemental sulfur is dissolved in liquid ammonia, new nucleophile species such as H2NS-NH4 + or H2NSS-NH4 + appear to be formed and to participate in the aromatic nucleophilic reactions. These new nucleophiles, H2NS-NH4 + and H2NSS-NH4 +, would undoubtedly participate in the reactions of 4,4′-dinitrodiphenyl disulfide (5) and 4,4′-dinitrodiphenyl sulfide (6) with elemental sulfur in liquid ammonia, respectively.

Novel generation and ring closure of 1,3-thiaza-1,3-butadiene S-oxides through thermal cycloreversion of 6H-1,3,5-oxathiazine S-oxides

Heating of 6H-1,3,5-oxathiazine S-oxides efficiently afforded 1,2,4-oxathiazoles through the mechanism involving thermal cycloreversion of the substrates and the subsequent ring closure of the intermediary 1,3-thiaza-1,3-butadiene S-oxides.

Pummerer-type α-functionalization of arylseleninylacetates by treating with trimethylsilyl- or tri-n-butylstannyl-masked nucleophiles and trifluoroacetic anhydride or a Lewis acid

Abstract Arylseleninylacetates underwent facile α-functionalization on treatment with trimethylsilyl- or tri- n -butylstannyl-masked nucleophiles and trifluoroacetic anhydride (TFAA) or a Lewis acid.

Regioselective monohalogenation of 3,3-disubstituted bornane-2-thiones via thione–dihalogen complexes

Abstract Reaction of 3,3-disubstituted bornane-2-thiones with Br2, ICl, or Cl2 afforded the corresponding 10-bromobornane-2-thiones, 10-iodobornane-2-thiones, or the products originated from skeletal rearrangement of 10-chlorobornane-2-thiones, respectively.

Reaction of 4-Nitrobenzenesulfenamide with Liquid Ammonia

Abstract Although numerous investigations on the chemistry of organic sulfenamides, for example, studies on the S–N torsional barrier,1 the electronic nature of the S–N bond2 and some nucleophilic substitutions on sulfur or nitrogen atom3 have been known, no example of nucleophilic substitution on arylcarbon of aromatic sulfenamides has been reported.

REACTION OF 4-NITROPHENYL 4′-NITROBENZENETHIOLSULFONATE WITH LIQUID AMMONIA

Abstract 4-Nitrophenyl 4′-nitrobenzenethiolsulfonate (1) reacted readily with liquid ammonia at room temperature to afford 4-nitrobenzenesulfenamide (2) and ammonium 4-nitrobenzenesulfinate (3). The products, (2) and (3), were found to react with liquid ammonia eventually affording various compounds, such as 4-nitroaniline (4), 4,4′-dinitrodiphenyl disulfide (5), 4,4′-dinitrodiphenyl sulfide (6), ammonium 4-nitrobenzenethiosulfonate (7), 4-nitrobenzenethiol (8) and 4-nitrophenyl 4′-aminophenyl sulfide (9). A reactive nucleophile, “H2NSx -NH4 +,” which is formed upon dissolving elemental sulfur, S8, in liquid ammonia, appears to play an important role in this reaction as in the reaction of 4-nitrobenzenesulfenamide with elemental sulfur in liquid ammonia.1

Oxidation of sterically-crowded selones using chloramine-T: generation and skeletal rearrangement of selone Se-imides

Abstract Treatment of sterically-crowded bornane-2-selones possessing substituted bornane skeletons with chloramine-T afforded several products originated from intermediary selone Se -imides, and the direct observation of the intermediates was performed by NMR monitoring at low temperature.

Novel Thiofomylation of Primary and Secondary Amines Using N-Aryl-1,2,3,4,5,7-Pentathiazocanes

Heating of N-aryl-1,2,3,4,5,7-pentathiazocanes 1 in the presence of primary and secondary amines afforded N-Alkyl or N,N-dialkylthioformamides 5, and similar heating of 1 in the absence of amines afforded an inseparable mixture of acyclic polysulfides 4 bearing a thioformanilide moiety on each terminal. Bisthioformanilides 4 were also converted into 5 by treating with these amines, and the thioformylation was assumed to proceed through a pathway involving the ring fission of 1 and the subsequent nucleophilic attack of these amines onto the thioformyl group of 4.