Annulation

About: Annulation is a research topic. Over the lifetime, 10152 publications have been published within this topic receiving 189701 citations.

Ruthenium-Catalyzed Electrochemical Dehydrogenative Alkyne Annulation

Abstract: A ruthenium-catalyzed electrochemical dehydrogenative annulation reaction of aniline derivatives and alkynes has been developed for the synthesis of indoles. Electric current is used to recycle the active ruthenium-based catalyst and promote H2 evolution. The electrolysis reaction is operationally convenient as it employs a simple undivided cell, proceeds efficiently in an aqueous solution, and is insensitive to air.

N‐Heterocyclic Carbene‐Catalyzed Enantioselective Annulation of Bromoenal and 1,3‐Dicarbonyl Compounds

Abstract: Highly enantioselective [3+3] annulation reactions of bromoenals and 1,3-dicarbonyl compounds are reported. In addition, both enantiomers of the resultant dihydropyranone could be easily obtained by choosing N-heterocyclic carbenes (NHCs) with the same stereocenter but different substituents under the optimized reaction conditions.

Mild rhodium(III)-catalyzed cyclization of amides with α,β-unsaturated aldehydes and ketones to azepinones: application to the synthesis of the homoprotoberberine framework.

Abstract: A novel synthesis of azepinone derivatives by using a Rh-catalyzed intramolecular annulation reaction of N-substituted benzamides and α,β-unsaturated aldehydes and ketones is developed.

C-C bond formation via C-H bond activation: synthesis of the core of teleocidin B4.

Abstract: The core of teleocidin B4, a complex fragment of a natural product containing two quaternary stereocenters and a penta-substituted benzene ring, was synthesized in four C-C bond-forming steps starting from tert-butyl derivative 1. The first step involved alkenylation of the tert-butyl group with a vinyl boronic acid, followed by the successful annulation of the cyclohexane ring to the benzene nucleus via an intramolecular Friedel-Crafts reaction. The third step required a diastereoselective oxidative carbonylation of the geminal dimethyl group, followed at last by indole assembly via the alkenylation of the phenol nucleus, to afford the teleocidin B4 core. Noteworthy is the fact that steps 1 and 3 critically depended on the directing role of the aniline nitrogen (directed C-H bond functionalization).