The Action of Sulfur on Indole

Anomalous Reactions in Attempts to Prepare 3-Alkylthioindoles

“…spectra, melting points, or boiling points with those of authentic samples, while those coinpounds not isolated were identified by their retention times or Xi values coinpared with those of ltnown compounds. The 3,3'-diindolyl (8) could be readily identified by its R f value (t.1.c.) and by its characteristic strong bluewhite fluorescence, first noted by Gabriel et nl.…”

“…Thin-layer chromatography indicated that the main product was indole. I t was also accompanied by a small amount of 3,3'-diindolyl, as shown by the strong blue-white fluorescence (9), a positive Ehrlich test (14), and comparison of its Rf value with that of an authentic specimen (8). Also, a t least nine other indole compounds were indicated by the Ehrlich spray on the thin-layer chron~atogram.…”

Synthetic, Spectroscopic, and X‐ray Crystallographic Studies of [1,2,7,8]Tetrathiacyclododecino[4,3‐b:5,6‐b′:10,9‐b′′:11,12‐b′′′]tetraindoles

“…For example, the dithiin 1 was claimed as a product from the treatment of the tetrasulfide 2 with sodium borohydride, followed by addition of acetic acid. [2] The isomeric dithiin 3 might theoretically, as has been discussed previously, [3] be formed by electrocyclization of its valence tautomer, dithioindigo (4). Although thionated derivatives of indigo (5) and indigoids have repeatedly been discussed in the literature over the years, neither 4 nor 6 have previously been isolated or characterized.…”

Thionation of bisindole derivatives with P4S10 or elemental sulfur

“…One of the earliest examples is the tetrasulfide 1 with a direct 3,3Ј-linkage between the indole units, and 1 is preferably prepared via the reaction of indole with elemental sulfur in hot DMF. 2 Compound 1 has probably already been obtained in 1938 by Szperl, however, it was not assigned a definite structure. 3 Later studies have demonstrated that 1 is a potent antifungal agent with particularly strong activity against Botrytis cinerea.…”