An efficient protocol for the synthesis of highly sensitive indole imines utilizing green chemistry: optimization of reaction conditions

Abstract

Novel and highly sensitive indole-based imines have been synthesized. Their synthesis has been compared employing a variety of protocols. Ultimately, a convenient, economical and high yielding set of conditions employing green chemistry have been designed for their synthesis.

Synthesis, characterization, and in vitro anti-cholinesterase screening of novel indole amines

“…We already reported the synthesis of imines (Schiff bases) involving a variety of reagents; however, the reflux of anilines with 7-formylindoles in dry EtOH afforded the best yields. 48 Therefore, the coupling of nitroanilines 17b–d with 7-formylindoles ( 13 / 15 ) was carried out by refluxing in dry EtOH.…”

“…1 and Table 1). 47,48 The indoles (9 and 11) were formylated by the reported Vilsmeier-Haack protocol, in which the formylating agent is the chloroiminium ion intermediate, generated by the interaction of DMF with POCl 3 . No prominent change in the N-H stretching was observed between indoles 9 and 11 (3343 and 3363 cm −1 , respectively) and 7-formylindoles 13 and 15 (3298 and 3347 cm −1 , respectively) in the infra-red (IR) spectra, which suggests that no H-hydrogen bonding exists between formylic O and indolic H. The C]O bending in the 7-formylindoles (13 and 15) appears at a very low value (1608 and 1647 cm −1 , respectively), which reveals that the aldehydic functional group is attached to a highly conjugated system.…”

“…1 and Table 1). 47,48 The indoles (9 and 11) were formylated by the reported Vilsmeier-Haack protocol, in which the formylating agent is the chloroiminium ion intermediate, generated by the interaction 15) appears at a very low value (1608 and 1647 cm −1 , respectively), which reveals that the aldehydic functional group is attached to a highly conjugated system. The bathochromic shi in the l max of 7-formylindoles 13 and 15 (372, 358 nm, respectively) was observed in contrast to indoles 9 and 11 (322, 318 nm, respectively), which indicates an increase in conjugation due to the induction of a formyl moiety to the indolic chromophore.…”

“…A small portion of this amorphous solid was crystallized from EtOAc for spectroscopic and spectrometric characterization. 48 3.3 Synthesis of 2,3-diphenyl-(1H)-indole-7-carbaldehydes (13,15) The indole 9 or 11 (3 mmol, 1 eq.) was added to a stirred solution of POCl 3 (0.85 mL, 1.4 g, 9 mmol, 3 eq.)…”

Electronic Impacts on the Solvent-Free Mechanochemical Synthesis of Salophen Ligands in Ball Mill

“…e manual grinding procedure, however, has limitations in terms of consistency and large-scale output. Furthermore, reports in the synthesis techniques employed in the Salophen ONNO ligand revealed that the synthesis was done in either solution media [18][19][20][21][22] or solvent-free [7,23] with at least one of the reactants in the liquid state. However, the former requires catalyzed, time-consuming, expensive, and environmentally harmful synthetic e ort, whereas the latter reactions are aided by liquid reactants and so do not reveal the entire extent of the solid-solid reaction.…”