Two facile accesses to mono-cinchona alkaloid-derived ligands, by conventional heating conditions and solvent-free microwave irradiation, are described. 1,4-Dichlorophthalazine (PHAL) or 3,6-dichloropyridazine (PYDZ) reacted with quinine (QN), cinchonine (CN), or cinchonidine (CND) by using CaH2 as acid-bonding reagent in DMF at 90-100C to provide mono-cinchona alkaloid-derived ligands 2a-f (87-95%) in 1.5h. However, the coupling reactions were performed under solvent-free microwave conditions to yield 2a-f (64-89%) within 15min.
Asymmetric Brominative Dearomatization of 2-Naphthols Using a Cinchona Alkaloid-Based Organocatalyst
作者:Kouhei Omae、Yoshihiro Miyake、Mio Shimogaki
DOI:10.1021/acs.joc.3c02945
日期:2024.3.15
A cinchonaalkaloid-basedorganocatalyst enables asymmetricbrominativedearomatization of 2-naphthols, providing the corresponding bromonaphthalenones with high enantioselectivities. The first metal-free reaction can accommodate a variety of functional groups and give useful frameworks bearing a Br-containing tetrasubstituted stereogenic center.