Exploiting the Divalent Nature of Isonitriles: a novel Pictet-Spengler Amidination process

One-pot tandem cyclisation to pyrrolo[1,2-a][1,4]benzodiazepines: a modified approach to the Pictet-Spengler reaction

We have reported a one-pot two-step methodology for the synthesis of highly condensed heterocycles, pyrrolo[1,2-a][1,4]benzodiazepines, by a modified Pictet-Spengler reaction under mild conditions in a short time. Our approach has a few advantages over the conventional two components synthesis as it is step and atom economic, environmentally benign and a convergent synthetic method. We have discussed here the broad substrate scope of this novel methodology.

Microwave Controlled Reductive Cyclization: A Selective Synthesis of Novel Benzimidazole-alkyloxypyrrolo[1,2-a]quinoxalinones

An efficient cascade synthesis of novel benzimidazole linked alkyloxypyrrolo[1,2-a]quinoxalinones was explored on soluble polymer support under microwave irradiation. Two exclusive protocols have been developed for the partial and full reductive cyclization by controlling the microwave energy. Commencing from the same substrate, ortho nitro pyrrol carboxylates, N-hydroxy pyrroloquinoxalinones were obtained by partial reductive cyclization (60 °C, 7 min), and the synthesis of pyrroloquinoxalinones was accomplished by full reductive cyclization (85 °C, 12 min). This method represents the first synthesis of N-hydroxy pyrroloquinoxalinones using Pd/C and ammonium formate as reducing agents. Further employing a variety of alkyl bromides, the obtained pyrroloquinoxalinones were transformed to their corresponding O- and N-alkylated analogues to deliver the diversified, novel molecular entities.