Indolothiopyrylium compounds. III. Pseudoazulenic thiopyrano [4, 3-b] indoles

TE Young, CJ Ohnmacht, CR Hamel…

Index: Young,T.E. et al. Journal of Organic Chemistry, 1967 , vol. 32, p. 3622 - 3626

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Citation Number: 2

Abstract

Dehydrogenation of 1, 3, 4, 5-tetrahydrothiapyrano [4, 3-b] indoles (8a-h) with chloranil or dicyanodichloroquinone gave 2-37% yields of the corresponding yellow-orange thiapyrano [4, 3-b] indoles (9a-h), which exemplify a new heteroaromatic ring system iso-a-electronic with benz [a] azulene. The nmr spectra of these pseudoazulenes (9) show two strongly deshielded protons characteristic of H-1 (6= 8.63-8.95 ppm) and H-4 (6= 8.10-8.27 ppm) ...