Shonosuke Zen

A stereoselective α-glucosylation by use of a mixture of 4-nitrobenzenesulfonyl chloride, silver tri-fluoromethanesulfonate, N,N-dimethylacetamide, and triethylamine

Abstract Stereoselective α-glucosylation of partially protected carbohydrates with 2,3,4,6-tetra-O-benzyl-α- d -glucopyranose in dichloromethane, in the presence of a quaternary mixture of 4-nitrobenzenesulfonyl chloride, silver tri-fluoromethanesulfonate, N,N-dimethylacetamide, and triethylamine gave O-α- d -glucopyranosyl-(1→4)- and 1(1→6)-2-acetamido-2-deoxy- d -glucopyranose (N-acetylmaltosamine and N-acetylisomaltosamine). A step-by-step synthesis of O-α- d -glucopyranosyl-(1→4)-O-[α- d -glucopyranosyl-(1→6)]- d - glucopyranose is described.

Synthesis of 2-amino-2-deoxy-D-hexopyranosides from 4-O-trichloroacetimidyl-D-hex-2-enopyranoside by [3,3]-sigmatropic rearrangement

2-Amino-2-deoxysugars, D-mannosamine and D-altrosamine derivatives were synthesized together with D-idosamine and D-talosamine ones from a 2-deoxy-2-trichloroacetamido-hex-3-enopyranoside. This key intermediate was prepared by regio- and stereoselective [3,3]-sigmatropic rearrangement of 4-O-trichloroacetimidyl-hex-2-enopyranoside.

New Heterocyclic Ring Systems: The Syntheses of 2H,3H,7H-Imidazo[1',2':1,2]pyrido[4,3-b]indoles and 2H,3H,4H,8H-Pyrimido[1',2':1,2]pyrido[4,3-b]indoles

Heterocyclic [1,2]-annulated pyrido[4,3-b]indoles (9 and 10) were syn- thesized in five step sequences starting from 4-hydrazino-1H-pyrid-2-one (1)

Formation of Novel Isoxazoline Spiro Compounds by a Reaction of Aryl Substituted a-Nitroacrylates with Titanium Tetrachloride and Toluene

New spiroisoxazoline derivatives were synthesized via novel cyclization of arylsubstituted α-nitroacrylates (naphthyl and phenanthryl analogues) with TiCl 4 and toluene. The structural determination by single crystal X-ray analysis is reported

Annulation of heterocycles via ring transformation of isoxazoline-2-oxides by Lewis acid

Novel heterocyclic-annulated furo[3,3a-d]isoxazoles were synthesized through the ring transformation reaction of heterocyclic ring-substituted isoxazoline-2-oxides promoted by Lewis acid such as titanium tetrachloride. Structural determinations by single crystal X-ray and nmr analyses are reported

TiCl4 promoted ring expansion reactions of 5-hydroxy-methyl-2-isoxazoline-2-oxide methanesulfonates

5-Hydroxymethyl-2-isoxazoline-2-oxide methanesulfonates(1) possessing a substituted phenyl ring were treated with TiCl 4 to afford either benzofuro[3,2-d]-1,2-oxazines(3) or 4-o-chlorophenyl-5,6-dihydro-4H-1,2-oxazines(4), depending on the nature of the substituents on the phenyl ring of 1. The reaction mechanism of the formation of 3 and 4 is proposed, including 3H-indole-1-oxide zwitterion(B) as a key intermediate

A Convenient Synthesis of Substituted Benzofuro[3,3a-d]-Isoxazole-3,4-Dicarboxylates and the Reaction Mechanism

Abstract A Lewis acid promoted novel ring transformation of 4-(p-halophenyl) -2-oxido-isoxazolirne-3, 5-dicarboxylates (1) provided 7-substituted-3a,4-dihydro-5aH-benzofuro-[3,3a-d]isoxazole-3,4-dicarboxylates (2) in good yields.

Synthesis of 4-(β-D-Ribofuranosyl)Isoxazoline N-Oxide Derivatives

Abstract Among numerous kinds of C-glycosyl heterocycles related to C-nucleoside antibiotics2, several 3- and 5- (C-glycosyl)isoxazolines and isoxazoles were reported by Tronchet and co-workers3. Other examples of 3- and 5-(β-D-ribofuranosyl)isoxazoles4 and their carbocyclic analogues5 have recently been demonstrated. General method of syntheses of the above heterocycles involves 1,3-dipolar cycloaddition of some olefinic or acetylenic dipolarophiles to sugar nitrile oxides, or the inverse cycloaddition.

Corrosion Inhibition of Copper and Chelate Formation by Some Organic Sulphur Compounds

ある種類のイオウ化合物として, 1-オキシピリジン-2-チオン, ジエチルジチオカルバミン酸ナトリウム, チオ尿素およびチオール類などを, 酸性浴中の銅の腐食抑制剤として用いた。これらはかなりの防食効果があり, その作用機構は従来の吸着説とは異なり, 銅表面に水に難溶性の対応する銅キレートの被膜が生成するためにその腐食が抑制されるとの結論を得た。すなわち, 銅表面から直接対応するキレートを抽出または採取し, 精製し, 別途合成した各対応する銅キレートと比較同定することができた。特に両者の比較に赤外線吸収スペクトルの結果を用い, また遠赤外領域の吸収から 386～342 および 281～205cm-1 におのおの ν(Cu-O) および ν(Cu-S) に基づくと推定できる吸収スペクトルを得ることができた。