Kodama K, Takase F, Hirose T. Direct enantioseparation of axially chiral 1,1′-biaryl-2,2′-diols using amidine-based resolving agents.
RSC Adv 2021;
11:18162-18170. [PMID:
35480945 PMCID:
PMC9033420 DOI:
10.1039/d1ra03546k]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 05/13/2021] [Indexed: 11/30/2022] Open
Abstract
Amidine-based optically active resolving agents for enantiomer separation of axially chiral 1,1′-biaryl-2,2′-diols have been developed. A strongly basic amidine bearing no substituents on its nitrogen atoms enables the formation of their diastereomeric salts upon being mixed with weakly acidic phenol derivatives. Enantiopure 1,1′-biaryl-2,2′-diols can be obtained in high yields after only one crystallization of their salts with the chiral amidine derived from dehydroabietic acid. X-ray crystallography revealed that the amidine moiety forms a salt with the phenol group and additional intermolecular NH/π interactions contribute to the efficient chiral recognition process.
Enantioseparation of atropisomeric biphenols using a chiral amidine derived from dehydroabietic acid was reported. Only one crystallization of their mixture gave pure diastereomeric salts of biphenols from racemate.![]()
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