Yasuo Tohda

Novel preparation of σ-alkynyl complexes of transition metals by copper(I) iodide-catalysed dehydrohalogenation

Transition metal alkynyl complexes have been prepared conveniently in high yields under mild conditions by the direct reaction of acetylenes with metal halides in the presence of catalytic amounts of copper(I) iodide in diethylamine.

Novel insertion of acetylene into σ-alkynyl palladium complexes

trans-[(PEt3)2PdCl(CCPh)] reacts with di-methyl acetylenedicarboxylate to give an insertion product, trans-[(PEt3)2PdCl {C(CO2Me)C(CO2Me)CC-Ph}], a type important in acetylene catalytic oligomerisation processes.

Novel functionalization of 1-methyl-2-quinolone; dimerization and denitration of trinitroquinolone

New methods for functionalization of 1-methyl-2-quinolone (MeQone) skeleton are provided. The reaction of 1-methyl-3,6,8-trinitro-2-quinolone (TNQ) with amines affords quinolone dimer 1 and 6,8-dinitroquinolone (6,8-DNQ). Dimerization predominantly proceeds at room temperature, and denitration takes place under heated and diluted conditions. We also provide a plausible mechanism for these reactions on the basis of structure–reactivity relationship of amines.

Improved generation method for functionalized nitrile oxide

Abstract Gentle generation of nitrile oxide bearing a carbamoyl group was performed. 4-Nitro-3-isoxazolin-5-one was treated with dipolarophiles in the mixed solvent ( MeCN H 2 O ) at room temperature to afford cycloadducts in good yields.

A novel nitrile oxide precursor ; 2-methyl-4-nitro-5(2H)-isoxazolone

2-Methyl-4-nitro-5(2H)-isoxazolone (1) was found to be a versatile precursor for a functionalized nitrile oxide by reaction with dipolarophiles giving 3-(N-methylcarbamoyl) isoxazole (2 or 3) derivatives

3,5-dinitro-1-(p-nitrophenyl)-4-pyridone as a novel protective group of primary amines

Abstract 3,5-Dinitro-1-(p-nitrophenyl)-4-pyridone is proposed as a novel protective group for primary amines, especially amino acids, based on the results of the transformation of 1-substituted 3,5-dinitro-4-pyridones with primary amines.

Synthesis and properties of tetrakisbridged parallel- and cross-orientation biphenylophanes

Abstract The two isomers of tetrakisbridged dimethoxybiphenylophanes, 1 and 2, have been synthesized. With respect to the longest wavelength absorption bands due to the biphenyl chromophores, the cross-orientation isomer exhibited the marked bathochromic shift, while the parallel-orientation isomer the typical exciton splitting. Their transannular properties in solution were further confirmed by X-ray crystal analysis.

Novel Synthesis of Substituted Pyrimidines: A Ring Transformation of 3-Methyl-5-nitropyrimidin-4(3H)-one

A novel ring transformation of 3-methyl-5-nitropyrimidin-4(3H)-one with ketones in the presence of ammonia was found to be an elegant method for synthesizing 5,6-disubstituted pyrimidines. Tetrahydroquinazoline was readily obtained in good yields when cyclohexanone was employed as a substrate. The present reaction was applicable to cyclopentanone, acetophenone and p-nitroacetophenone to give the corresponding pyrimidine derivatives

A ring transformation of 1-substituted 3,5-dinitro-2-pyidones

Abstract Reaction of 1-substituted 3,5-dinitro-2-pyridones with sodium salts of β-keto esters gave the ring transformation products, phenol derivatives and N -substituted nitroacetamides. Nonionic bicyclic intermediates could be isolated.

Synthesis and photophysical properties of [3.3](3,9)carbazolophanes

Syn- And anti-[3.3](3,9)carbazolophanes, which are suitable model compounds for sandwich and partial-overlap excimers, respectively, have been synthesized and characterized; the structures of both singlet and triplet carbazole excimer have been described.