Diastereoselective Synthesis of Carbohydrate Conjugates: Pyrano[3,2-c]quinolones

Abstract

A facile and efficient protocol for the diastereoselective synthesis of pyrano[3,2-c]quinolone carbohydrate derivatives from Perlin aldehydes and 4-hydroxyquinolones has been developed using a one-pot condensation at room temperature. In this investigation, glucose and galactose were employed as inexpensive starting materials to synthesize two sets of pyrano[3,2-c]quinolone-based carbohydrate conjugates. A total of sixteen novel compounds were successfully synthesized using this methodology in good to excellent yields. The reaction exhibited remarkable diastereoselectivity, resulting in a single diastereomeric product with a diastereomeric excess (dr) 97:3 for glucose, while a diastereomeric mixture with a diastereomeric excess (dr) 67:33 was obtained for galactose. The structural characterization of all sixteen compounds was carried out using various analytical techniques, including IR, 1H NMR, 13C NMR, 1H-1H COSY, 1H-13C HETCOR experiments, 2D NOESY NMR, and HRMS data. Additionally, the scalability of the protocol was successfully demonstrated by synthesizing one of the compounds on a gram scale, highlighting its potential for large-scale production.

An efficient synthesis of mono-, di-, and tri-substituted 1,3-thiazoles employing functionalized thioamides as thiocarbonyl precursors

“…In addition to our on-going work on the synthesis of novel heterocyclic molecules and unique synthetic techniques utilizing a variety of intermediates such as methyl dithiocarboxylates, xanthate esters, and 2-oxo-2-(amino) ethanedithioates, 16–25 herein, we developed an operationally simple and novel method for the synthesis of mono-, di- and tri-substituted thiazoles using alkyl 2-amino-2-thioxoacetates intermediates.…”

SnCl2-catalyzed multicomponent coupling: synthesis of 1,3-oxazolidine derivatives using paraformaldehyde as a C1 feedstock

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