Application of the Modified Pictet−Spengler Cyclization Reaction for the Preparation of an Imidazopyrazine Ring: Synthesis of new Pyrido- and Pyrimido-imidazopyrazines

Cyclocondensation reactions of an electron deactivated 2-aminophenyl tethered imidazole with mono/1,2-biselectrophiles: synthesis and DFT studies on the rationalisation of imidazo[1,2-a]quinoxaline versus benzo[f]imidazo[1,5-a][1,3,5]triazepine selectivity switches

Microwave-assisted cyclocondensation of title compounds afforded unreported imidazo[1,2-a] quinoxaline and benzo[f]imidazo[1,5-a][1,3,5]triazepines in high yields.

An efficient lactamisation/N-acyliminium Pictet–Spengler domino strategy for the diasteroselective synthesis of polyhydroxylated quinoxalinone, β-carboline and quinazolinone derivatives

A novel Pictet–Spengler cascade sequence has been developed. It involves a lactamisation/N-acyliminium key step and gives a diverse set of sugar-derived fused polycyclic heterocycles diastereoselectively and efficiently.

Regioselective synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats on an ionic liquid support

An ionic liquid supported synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats was explored to generate polycyclic imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats during the cleavage of the support.

Engineering of indole-based tethered biheterocyclic alkaloid meridianin into β-carboline-derived tetracyclic polyheterocycles via amino functionalization/6-endo cationic π-cyclization

A mild, efficient and versatile method has been developed for the construction of a functionalized natural product, meridianin, and its post conversion to pyrimido-β-carboline by cationic π- cyclization. The strategy involves the introduction of an amino group at the C-5 of the pyrimidine ring and utilizing the nucleophilictiy of the C-2 in the indole ring to facilitate cationic π-cyclization.

Straightforward assembly of phenylimidazoquinoxalines via a one-pot two-step MCR process

An efficient multicomponent-based methodology providing a new entry into a medicinally important complex heterocyclic core is presented. The strategy is very general and able to endow target compounds with the highest possible number of diversity points. Notably, four new chemical bonds and two aromatic rings are formed in a one-pot fashion.