Synthesis of tetrahydroindeno[1,2-b]indol-10-ones and their rearrangement to [2]benzopyrano[4,3-b]indol-5-ones

Isomerization of Ninhydrin–Heterocyclic Ketene Aminal Adducts: Kinetic versus Thermodynamic Control, Solvent Dependency and Mechanism

“…Actually, the reaction chemistry of NIN with anilines has been investigated previously: Shapiro et al reported that the NIN‐anilines adducts were indeno[2,1‐ b ]pyrrol‐8(1 H )‐ones 21. However, re‐examination of these reactions by Bullington et al22 or Black et al23 corrected that the products should be the 2‐aryl‐2‐hydroxy‐1,3‐indanediones. Although our efforts to isomerize 5 – 7 failed, further investigation is required to establish whether the isomerization exits only in NIN–HKA adducts.…”

Novel compounds from 1,2-indanedione and 3,5-dimethoxyaniline

“…Reactions involving ninhydrin and electron-rich anilines have been reported (Black et al, 1994;Bullington & Dodd, 1993;Friedman, 1967;Shapiro & Chatterjie, 1970). These investigations have found that the products are highly dependent on both the aniline and the conditions employed.…”

“…From these reactions, several possible products may be formed, as ninhydrin possesses multiple electrophilic sites and the anilines, in many cases, possess several nucleophilic sites. As a result, much debate has taken place as to the regiochemistry of these compounds (Bullington & Dodd, 1993;Shapiro & Chatterjie, 1970). These investigations prompted us to examine the reaction of 1,2-indanedione and 3,5dimethoxyaniline.…”

Ninhydrin in synthesis of heterocyclic compounds

“…Anilines, having only one electron-donating group located at the meta position, react para to the amine, and therefore cannot lead to ring closure, resulting in the formation of the tetrahydroindeno[1,2-b]indolone product not being possible. 160 A one-pot four component procedure for the synthesis of densely functionalized pyrroles 46 by reacting ninhydrin with phosphorane intermediates 43 was developed by Azizian et al (Scheme 11). 161 The latter is produced from the reaction between triphenylphosphine, ammonium thiocyanate (or ammonium acetate) and various dialkyl acetylenedicarboxylates 41.…”

“…74,160 With this in mind, Pramanik and co-workers reported refluxing 206 with urea in acetic acid (one pot reaction) to produce isoindole fused imidazoles with phenolic subunits 207 (Scheme 60). 271 It was observed that in aprotic solvent, they show high fluorescent properties, but in protic polar solvent, fluorescent intensity decreases.…”