Synthesis of tetrahydroquinazolines from 2-aminobenzonitriles and alkylidene malonates via 1,4-conjugate addition and an unprecedented rearrangement reaction.

An efficient methodology for the synthesis of highly diverse tetrahydroquinazoline scaffolds from 2-aminobenzonitriles and alkylidene malonates via 1,4-conjugate addition followed by an unprecedented rearrangement has been demonstrated. The methodology is further applicable for the synthesis of quinazolines and tetracyclic compounds. Some of the synthesized compounds exhibit photophysical properties.

Base-Promoted [4 + 2] Annulation Reaction of In Situ-Generated Azadienes from N-Propargylamines with Active Methylene Compounds: Access to Highly Functionalized 2-Pyridones.

A facile and efficient synthesis of structurally diversified 2-pyridones is demonstrated using the [4 + 2] annulation of in situ generated azadienes from N-propargylamines and active methylene compounds. The reaction is promoted by an inorganic base giving moderate to good yields. The developed methodology is applicable for the direct and formal synthesis of various bioactive molecules. The synthetic utility of the protocol was also illustrated by late-stage functionalization of the products.

Temperature Tunable Synthesis of Tetrahydro-4H-pyrrolo[3,2-c]quinolin-4-ones and Dihydro-1H-benzo[b]azepines from 2-Aminobenzonitriles and Donor-Acceptor Cyclopropanes.

Tetrahydro-4H-pyrrolo[3,2-c]quinolin-4-ones and dihydro-1H-benzo[b]azepines are efficiently synthesized from 2-aminobenzonitriles and donor-acceptor cyclopropanes mediated by SnCl4 in moderate to good yields. The reaction involves the initial ring opening of a cyclopropane ring due to activation by SnCl4 followed by nucleophilic attack by amine to give an adduct, which after unprecedented rearrangement at two different reaction temperatures provides two nitrogen heterocyclic compounds. This methodology can be used for the synthesis of hexahydropyrrolo[3,2-c]quinolinone derivatives, the structure of which is found in biologically active molecules.

Synthesis of pyrimido[2,1-a]isoindolone and isoindolo[2,1-a]quinazolinone via intramolecular aza-Prins type reaction.

A novel aza-Prins type cyclization reaction involving N-acyliminium ions and amides is reported for the synthesis of tetrahydropyrimido[2,1-a]isoindole-2,6-dione and 6,6a-dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives in excellent yields. The strategy features inexpensive reagents, mild reaction conditions, and metal-free synthesis of N-heterocyclic frameworks. Further, post-synthetic modification results in the unprecedented formation of its triazole, tetracyclic diazacyclopenta[def]phenanthrene-1,4(9a1H)-dione and carbonyl derivatives.