Asymmetric Synthesis of Imidazo[2,1‐a]isoquinolin‐3‐ones with Dihydroisoquinolines and N‐substituted Amino Acids

Abstract

A mild direct synthesis of chiral imidazo[2,1‐a]isoquinolin‐3‐one derivatives with dihydroisoquinolines and N‐substituted amino acids have been developed. By the use of easily accessible DCC as condensation reagent at ambient temperature, a series of imidazo[2,1‐a]isoquinolin‐3‐ones can be assembled readily in low to good yields with low to excellent dr values. Interestingly, the use of N‐substituted L‐Threonine and L‐Serine afforded oxazino[2,3‐a]isoquinolin‐4‐one derivatives with good diastereoselectivities.

Imidazopyridine Family: Versatile and Promising Heterocyclic Skeletons for Different Applications

“…Moreover, imidazoquinolines correspond to various structures (such as imidazo[5,1- a ]quinolines and imidazo[2,1- a ]isoquinolines) in which a third aromatic ring connects to the imidazopyridine nucleus. These derivatives represent the extension of the aromatic system of the classic imidazopyridines; the extended delocalized system alters their optical, structural, and solubility properties, sometimes presenting a promising structural alternative to the common heterocyclic ring such as phenanthroline, carbazole, benzoquinoline, acridine, and many others [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ].…”

Synthesis of Polycyclic Imidazolidinones via Cascade [3 + 2]-Annulation of β-Oxo-acrylamides with Cyclic N-Sulfonyl Imines

“…In contrast, studies on the asymmetric synthesis of enantiopure 4-imidazolidinones remain rare. One of the most extensively utilized and easy procedures is the condensation reaction between carbonyl compounds and chiral amino acid derivatives (Scheme a) . Alternative methods include the following: Ti-catalyzed asymmetric addition of dialkylzinc reagents to α-aldiminoesters (Scheme b), imidazolidinone-derived β-amidoesters undergoing decarboxylative asymmetric allylic alkylation under the catalysis of Pd (Scheme c); under Ru catalysis, 2-azidoacetamides undergoing enantioselective ring-closing C–H amination (Scheme d), and I 2 or KI-catalyzed intramolecular dehydrogenative coupling reaction of α-amino acid derivatives (Scheme e) .…”