Kazuho Harada

Synthesis of Di- and Trisaccharides Comprising D-Fructopyranose with β2 → 1 Glycosidic Linkage Using β-D-Fructopyranosyl Fluoride as the Fructosyl Donor

D-Fructose was converted into a stable, suitably protected fructosyl donor for iterative glycosylation, i.e., 1-O-acetyl-3,4,5-tri-O-benzyl-β-D-fructopyranosyl fluoride and a fructosyl acceptor, methoxymethyl 3,4,5-tri-O-benzyl-β-D-fructopyranoside in good yields. Glycosylation of the both substrates provided di- and trisaccharides comprising p-D-fructopyranose with β (2→1)-interglycosidic linkage.

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)

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

Tautomeric structure of dihiydropyridazino-[3,4-b]quinoxalines in solution and solid state

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide (1) with β-diketone abd β-ketoesters gave the dihydropyridazino[3,4-b]quinoxalines (IIIa-d), which were found to exist as the 1,5-dihydro form in solution and solid state by NMR spectoscopy and x-ray analysis.