Design and application of intramolecular arylogous nitroaldol condensation to access 2-aryl-benzofuran and -indole derivatives and formal synthesis of saprisartan.

This study presents the design and application of intramolecular arylogous nitroaldol (Henry) condensation. A transition metal-free, base-mediated reaction of -heteroatom-substituted aryl aldehydes/ketones and 2-nitrobenzyl (pseudo)halides has been developed to access a wide range of 2-(2-nitroaryl)benzofuran/2-(2-nitroaryl)indole derivatives in high yields. The reaction appears to proceed through -/-benzylation and intramolecular arylogous nitroaldol condensation.

Carbene-Catalyzed Tandem Imine Umpolung-Intramolecular Aza-Conjugate Addition-Oxidation to Access -Substituted Isoindolinones.

Herein, we have described a novel N-heterocyclic carbene (NHC)-catalyzed synthesis of -substituted isoindolinone acetates. The presented transformation proceeds through NHC-catalyzed tandem imine umpolung-intramolecular aza-Michael addition followed by oxidation, while molecular oxygen in air acts as a sole oxidant. Atom efficiency, operational simplicity, large-scale syntheses, and mild reaction conditions are the salient features of this method.

Design and development of intramolecular doubly vinylogous Michael addition to access 3-aryl substituted 2-alkenyl-benzofurans and -indoles.

Herein, we have disclosed a rare example of an intramolecular doubly vinylogous Michael addition (DVMA). The reaction design exploits the innate reactivity of -heteroatom substituted -quinone methide (-QM) derivatives. The sequential reaction of -QMs and activated allyl halides proceeds through heteroatom-allylation, DVMA and oxidation to furnish a diverse range of 2-alkenyl benzofuran and 2-alkenyl indole derivatives in high yields.