2745-07-5Relevant academic research and scientific papers
Synthesis and Reactions of 2-Arylhydrazinotropones. II. Synthesis of 5-Aryltropolones and B-Ring-Open Colchicine Analogues via Benzidine Type Rearrangement of 2-(2-Arylhydrazino)tropones
Nozoe, Tetsuo,Takase, Kahei,Yasunami, Masafumi,Ando, Masayoshi,Saito, Hiroaki,et al.
, p. 128 - 142 (2007/10/02)
Treatment of a wide variety of 2-(2-arylhydrazino)tropones with ethanolic acid at 50-80 deg C readily gave the benzidine type rearrangement products, 2-amino-5-(4-aminoaryl)tropones, besides minor amounts of byproducts of various type.The main products were conveniently led to the corresponding 5-aryltropolones.Similarly, 2-(2-arylhydrazino)tropones bearing an isopropyl and isopropenyl group at the 4-position afforded 4-substituted 2-amino-5-(4-aminoaryl)tropones as the main products, which were also led to 4-substituted 5-(4-acetamidoaryl)- and 5-(4-methoxyaryl)tropolones.Structural assignments of these products were made on the basis of 1H NMR and other spectral data as well as of chemical transformations to known 5-phenyltropolone and also to 2-acetamido-8-hydroxy-10,10-dimethylcycloheptinden-7(10H)-one.This synthetic scheme may possibly be utilized for a convenient synthesis of B-ring-open analogues of colchicine.
Synthesis and Reactions of 2-Arylhydrazinotropones. I. Preparation of 2-(2-Arylhydrazino)tropones and the 4-Substituted Derivatives
Nozoe, Tetsuo,Imafuku, Kimiaki,Yin, Bing-Zhu,Honda, Masaaki,Goto, Yasutomo,et al.
, p. 2531 - 2540 (2007/10/02)
A wide variety of 2-(2-arylhydrazino)tropones were prepared by the reactions of 2-tosyloxytropone with arylhydrazines.The dimeric compounds 6,6'-bis(arylhydrazono)-1,1'-bi(2,4-cycloheptadiene)-7,7'-diones, 2-anilinotropones, and 3-(2-arylhydrazino)tropones were isolated as minor products in some cases.Similarly, starting with 2-tosyloxytropones bearing an isopropyl, isopropenyl, (1-acetamidoethyl), and protected acetyl group at the 5-position, 4-substituted 2-(2-arylhydrazino)tropones were obtained as the major products by the abnormal substitution reaction.These 2-(2-arylhydrazino)tropones are expected to effectively serve as precursor for a convenient synthesis of 5-aryl-substituted tropolones via benzidine-type rearrangement. 1H NMR (200 or 500-MHz) parameters for these 4-substituted 2-(2-arylhydrazino)tropones are given for their unambiguous structural assignments.
A Convenient Synthesis of 5-Aryltropolones via Novel Benzidine Type Rearrangement of 2-(2-Arylhydrazino)tropones
Nozoe, Tetsuo,Takase, Kahei,Saito, Hiroaki,Yamamoto, Hiroshi,Imafuku, Kimiaki
, p. 1577 - 1580 (2007/10/02)
Treatment of a wide variety of 2-(2-arylhydrazino)tropones with ethanolic acid at 50-80 deg C readily gave the benzidine type rearrangement products, i.e. 2-amino-5-(4-aminoaryl)tropones, which in turn were conveniently led to the corresponding 5-aryltropolones that can be utilized for synthesizing B-ring-open analogues of colchicine.
