Masahiro Ariga

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

An anomalous hydration/dehydration sequence for the mild generation of a nitrile oxide

A nitrile oxide containing a carbamoyl group is readily generated upon the treatment of 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with water under mild reaction conditions, even in the absence of special reagents. The obtained nitrile oxide undergoes cycloaddition with dipolarophiles, alkynes and alkenes, to afford the corresponding isoxazol(in)es, which are useful intermediates in the synthesis of polyfunctionalized compounds. A plausible mechanism underlying the formation of the nitrile oxide is proposed, which involves an anomalous hydration/dehydration sequence. DFT calculations were also performed to support this mechanism.

Synthesis of 4‑Substituted 3,5-Dinitro-1,4-dihydropyridines by the Self-Condensation of β‑Formyl-β-nitroenamine

3,5-Dinitro-1,4-dihydropyridines (DNDHPs) are readily constructed by the acid-promoted self-condensation of β-formyl-β-nitroenamines. In the DNDHPs, one molecule of the nitroenamine serves as a C3N1 building block and the other serves as a C2 block. This synthetic method does not require any special reagents and conditions. When the reaction is conducted in the presence of electron-rich benzene derivatives, arylation at the 4-position of DNDHP is achieved by trapping the 3,5-dinitropyridinium ion intermediate.

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.

The synthesis and properties of a methylviologen analogue

Abstract A novel derivative of methylviologen, prepared by transannular reaction of [2.2] (3,5) pyridinophane, shows large bathochromic shift in the electronic spectrum and nearly equal redox potential compared with methylviologen.