Comparative study of different chiral ligands for dynamic kinetic resolution of amino acids

Abstract

Dynamic kinetic resolution (DKR) of unprotected amino acids (AAs), via intermediate formation of Ni(II) complexes, is currently a leading methodology for preparation of natural and tailor-made AAs in enantiomerically pure form. In this work, we conduct a comparative case study of synthetic performance of four different ligands in DKR of six AAs representing aryl-, benzyl-, alkyl-, and long alkyl-type derivatives. The results of this study allow for rational selection of ligand/AA type to develop a practical procedure for preparation of target enantiomerically pure AAs.

Radiosynthesis and Preclinical Evaluation of m-[18F]FET and [18F]FET-OMe as Novel [18F]FET Analogs for Brain Tumor Imaging

“…Alternatively, esterification of ( RS )- m -Tyr to ( RS )- m -Tyr-OMe followed by N -Boc protection, 33 alkylation with 1-fluoro-2-iodoethane, and two-step deprotection were used to prepare racemic HCl·( RS )- m -FET in 25% yield over five steps. Subsequent retro-racemization of HCl·( RS )- m -FET according to the protocol of Nagaoka et al 48 via Ni-BPB complex 5 afforded m -FET in 60% yield over two steps ( Scheme 1 ).…”

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

“…Asymmetric synthesis of functionalized amino acids is a subject of intense research because these compounds are of great demand for pharmaceutical industry, health care, and food production [ 1 – 3 ]. Various approaches to enantiomerically enriched amino acids have been developed employing chiral auxiliaries [ 4 – 5 ] and asymmetric phase-transfer catalysis [ 6 – 7 ]. The former approach is commonly based on the application of chiral derivatives of glycine containing structurally diverse chiral auxiliaries, both cyclic [ 8 – 11 ] and acyclic [ 12 – 13 ].…”