Related Experiment Video
Updated: Apr 12, 2026

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source
Published on: August 17, 2018
Organocatalyzed oxidative N-annulation for diverse and polyfunctionalized pyridines
Hari Datta Khanal1, Yong Rok Lee
1School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea. yrlee@yu.ac.kr.
Abstract:
This paper describes a novel strategy for the synthesis of 2,3,4-trisubstituted pyridines via organocatalyzed three-component reactions. A variety of pyridine derivatives are synthesized from readily available ketones with α,β-unsaturated aldehydes and ammonium acetate under a mild organocatalyst. This protocol leads to rapid N-annulation through C-C and C-N bond formation in a single operation, thereby avoiding the preparation of essential functional groups, such as oximes, imines, or azides. The synthesized compounds are used for the evaluation of antibacterial activities and as fluorescence sensors for Cu(2+) ions.
Related Concept Videos
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

