Masao Okamoto

Functional masking of carbonyl group by 1-methyl-1H-imidazol-2-YL moiety

Abstract Easily obtained 1-methyl-2-(1′-hydroxyalkyl)-1H-imidazoles (4) were found to be a new type of masked form for carbonyl group which could survive under various severe conditions. The corresponding carbonyl compounds (3) were easily reproduced by quarternization of the imidazole (4) with CH 3 I followed by aqueous basic treatment. 2-Acyl-1H-imidazoles (5) were convertible to aldehydes or ketones (3) by using the present methodology.

A convenient one-pot procedure for synthesis of thiol esters using magnesium ion as a catalyst

Abstract Various thiol esters (R 1 COSR 2 ) were prepared in high yields by treatment of 1-acylimidazole with thiols in the presence of a catalytic amount of Mg(OEt) 2 . Malonic half-thiol esters [R 1 OCOCH(R 3 )COSR 2 ] were also prepared in good yields by treating magnesium monoalkyl malonate [R 1 OCOCH(R 3 )COOMg 1 2 ] with carbonyl-1,1′-diimidazole followed by addition of thiols.

Photochemical Fries Rearrangement of N-Phenyl-2-pyrrolidone

Photochemical Fries rearrangement of 1-phenyl-2-pyrrolidone (1) proceeded smoothly in methanol especially in the presence of piperylene. Continuous photo-irradiation of 1 successfully was carried out to raise the yield by utilizing a reaction mixture-circulation system consisting of a spiral quartz cell, a pump, a uv light source and a column packed with appropriate absorbents for the Fries rearranged product (3) and pigments

Synthesis of novel 5- and 6-substituted 3-arylidene-1,4-oxathiin-2(3H)-ones

The reactions of α-acetylthio-β-arylacrylic acids (2a–c) with α-halogeno ketones (3a–f), α-halogeno-β-keto esters (7a–b), and α-halogenopyruvate (9) afforded the corresponding novel 3-arylidene-1,4-oxathiin-2(3H)-ones [(4a–d), (8a–f), and (10a), respectively] having 5- and/or 6-substituents. The β-aryl-α-thioacrylic acids (1a–d) were treated with α-halogeno ketones (3a–f), (7a–b), and (9) to give the corresponding β-aryl-α-alkylthioacrylic acids (5a–d), (11a–f), and (12a–c), which were converted into the respective 3-arylidene-1,4-oxathiin-2(3H)-ones (4a–g), (8a–f), and (10a–c) by intramolecular cyclization when treated with thionyl chloride–dimethylformamide. The sulphur atom of the 1,4-oxathiin-2(3H)-ones (4d), (4g), and (8a) was smoothly oxidized with m-chloroperbenzoic acid to give the corresponding S-oxides (13a–c) in good yields.