Toshio Itahara

NMR study of 9,9′-(alkane-α,ω-diyl)diadenine

The relationship between NMR chemical shifts of adenine ring protons of low concentrations of 9,9′-(alkane-α,ω-diyl)diadenine and the length of the polymethylene chains has been investigated in buffer solutions at pD 1.0, 7.0 and 13.0 and in organic solvents such as CD3OD,(CF3)2CDOD, [2H6]dimethyl sulfoxide and CF3COOD. The chemical shifts were compared with those of 9-(ω-bromoalkyl)adenine.

Alkenylation of 1-acylindoles with olefins bearing electron-withdrawing substituents and palladium acetate

The oxidation of 1-(2,6-dichlorobenzoyl) indole with olefins, such as alkyl acrylates and acrylonitrile, and palladium acetate resulted in selective 3-alkenylation of the indole nucleus. Treatment of 1-acyl-3-methyl-indoles under similar conditions gave the corresponding 2-alkenyl substituted indoles, while the oxidation of 6-oxo-6H-isoindolo[2,1-a]indole gave the corresponding 3-alkenyl substituted indoles.

THE ROLE OF DIOXYGEN SPECIES IN THE BASE‐ AND COBALT‐CATALYZED OXYGENATION OF HINDERED PHENOLS

Abstract— The mechanisms by which 4‐substituted 2,6‐di‐t‐butylphenols are oxygenated by base‐ and Co(II) Schiff base complex‐catalysis into o‐ or p‐peroxyquinols and their Co(III) complexes, respectively, have been investigated. For the base‐catalyzed oxygenation, a one‐step ionic mechanism involving no radical species is suggested to be the most probable one. For the formation of the peroxycobalt(III) complexes, the following stoichiometry is concluded: ArOH + Co(II) + 5/4 O2→ peroxycobalt(III) complex + 1/2 H2O. A mechanism involving an electron transfer between the phenols and the Co(II)‐O2 complex followed by further electron transfer between the formed phenoxy radicals and the Co(II) complex to give the corresponding phenolate anions is proposed.

Base-catalyzed oxygenation of 2,6-di-t-butylanilines: X-ray analysis of 2,4,6-tri-t-butyl-4,5-epoxy-6-hydroxy-2-cyclohexen-1-imine

Abstract Oxygenation of 2,4,6-tri-t-butylaniline (1a) catalyzed by t-BuOK in hexamethylphosphoric triamide (HMPA) at 75° leads to the incorporation of molecular oxygen into the aromatic ring giving rise to 2,4,6-tri-t-butyl-4,5-epoxy-6-hydroxy-2-cyclohcxen (12a). A similar result is obtained in the oxygenation of 2,6-di-t-butyl-4-phenylaniline (11b). The oxygenation of 11a in toluene containing n-BuLi gave exclusively 2,4,6-tri-t-butyl-nitrosobenzeoe. The oxygenation of 2,6-di-t-butyl-4-methoxyaniline (1d) in tetrahydrofuran with n-BuLi gave dimeric products in fairiy good yields. The structure of 12a has been confirmed by X-ray analysis. The crystals are monoclinic ( P2 1 a ) with a = 9.99, b = 23.16, c = 8.70 A, β = 116.19°; Z = 4. The structure was determined by direct methods and refined to R = 0.089.