Carbon Dioxide Incorporation Reaction for Organic Synthesis

Title:

Carbon Dioxide Incorporation Reaction for Organic Synthesis

Schedule:

Date: 27^th November, 2023 (Monday)

Time: 5:30 - 6:30 pm (HKT)

Venue: Lecture Theatre P1, Chong Yuet Ming Chemistry Building

Speaker:

Prof. Tohru YAMADA

Department of Chemistry

Keio University

Abstract:

It was reported that the combined use of a catalytic amount of silver acetate and DBU efficiently catalyzed the incorporation of CO2 under mild reaction conditions for a wide range of propargyl alcohols to afford the corresponding cyclic carbonates in high-to-excellent yields. This procedure can be applied to various alkyne containing substrates to afford the corresponding heterocycles. In some polar solvents, such as formamides, the corresponding enone compounds generated via a decarboxylative Meyer-Schuster type reaction were realized. Through the reaction of conjugated ynones with CO2 catalyzed by silver salt, facile and versatile access to highly functionalized tetronic acids has been achieved and successfully applied to synthesis of Aspulvinone E. In these reactions, the vinyl-silver intermediates were considered. In the presence of electrophiles, such as NIS, NBS and DEAD, the silver atom will be replaced by those electrophiles to afford the corresponding functionalized vinyloxazolidinone derivatives stereoselectively. Without silver catalyst, Kolbe–Schmitt type reaction for resorcinols under ambient conditions was achieved with the combined use of an organic base. Recently, we reported the decarboxylative Nazarov type reaction to afford the highly substituted2-cyclopentenones from the corresponding cyclic carbonate, prepared with the silver-catalyzed CO2 incorporation into propargyl alcohol derivatives. When the carbonate was treated with catalytic amount of BF3•OEt2 in 1,2-dichloroethane at room temperature, the Nazarov cyclization proceeded to afford trans-2-cyclopentenones with high stereoselectivity. This procedure can be applied to the chirality transfer system to afford the corresponding 2-cyclopentenones in optically pure form.

- ALL ARE WELCOME -