Synthesis of novel crown ether-squaramides and their application as phase-transfer catalysts

Fehér, Zsuzsanna and Richter, Dóra and Nagy, Sándor and Bagi, Péter and Rapi, Zsolt and Simon, András and Drahos, László and Huszthy, Péter and Bakó, Péter and Kupai, József (2021) Synthesis of novel crown ether-squaramides and their application as phase-transfer catalysts. MOLECULES. ISSN 1420-3049 (Submitted)

Preview

Text Manuscript_Feheretal.pdf Download (569kB) | Preview

Abstract

t: This work presents the synthesis of six new phase-transfer organocatalysts where the 15 squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, 16 namely hydroquinine, quinine, cinchonine (cinchonas), and α-D-glucopyranoside were responsible 17 for the asymmetric construction of an all-carbon quaternary stereogenic center in α-alkylation and 18 Michael addition reactions of malonic esters. We intended to investigate the effects of different chi- 19 ral units and that of crown ethers with different sizes on catalytic activity and enantioselectivity. 20 During extensive parameter investigations, both conventional and emerging green solvents were 21 screened, providing valuable α,α-disubstituted malonic ester derivatives with excellent yields (up 22 to 98%). Furthermore, the products are amenable to chemoselective transformation and could be 23 successfully converted to the corresponding α,α-disubstituted amino acid derivatives through Cur- 24 tius rearrangement.

Actions (login required)

Edit Item