The indophenine reaction revisited. Properties of a soluble dialkyl derivative

• Published in: Journal of the American Chemical Society Vol. 115; no. 24; pp. 11512 - 11515
• Main Authors: Tormos, Gregory V, Belmore, Kenneth A, Cava, Michael P
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.12.1993; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with n hetero atom and also o and/or s, se, te hetero atoms; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Five membered ring; Sulfur heterocycle; Side reaction; Dyes; Nitrogen heterocycle; Bicyclic compound; Reaction mechanism; Soluble compound; Aromatic compound; Thiophene; Sulfuric acid
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00077a057

The classical indophenine reaction of thiophene with isatin and sulfuric acid has been reinvestigated using N-heptylisatin, which affords soluble reaction products amenable to chromatographic purification. An NMR analysis of the resulting indophenine blue (8) has shown it to be a mixture of all six possible geometric isomers (8a-f) of the previously assumed gross structure. The intermediacy of alcohol 11 in the formation of 8 is strongly supported. In addition, an indophenine analog (9a) derived from only one thiophene unit is reported for the first time.