Concepts for ligand design in asymmetric catalysis: a study of chiral amino thiol ligands

Chiral ligand optimization in the asymmetric zirconium–zinc transmetalation aldehyde addition reaction

“…Conversion of the hydroxy moiety to the thioacetate utilizing Mitsunobu reaction conditions followed by LiAlH 4 reduction afforded the desired ligands 8a and 8b. 25 Analogously, ligand 8c was synthesized starting from (S)-t-leucinol in the manner described earlier.…”

Application of N,S-chelating chiral ligands and zinc complexes in catalytic asymmetric hydrosilylation using polymethylhydrosiloxane

“…Indeed many studies have demonstrated the superiority of catalysts incorporating amino and sulfur groups compared to amino alcohols. 7 Applications in asymmetric catalysis such as hydrogenation, 8 allylic alkylation, 9 organozinc additions, 7 Grignard cross-coupling and hydrosilylation of imines and ketones 9 have demonstrated the interest of these classes of chiral ligands. The electronic properties of sulfur compared to oxygen and the higher affinity of thiols and thiolates towards soft metal, especially zinc, could explain these results.…”

Versatile Synthesis of Secondary 2‐Amino Thiols and/or Their Disulfides via Thiazolinium Salts

“…Although some secondary 2‐amino thiols, as well as their disulfides, have found interesting applications as ligands in transition‐metal catalysis2c,4 and in medicinal chemistry,5 their application remains limited mainly because of the poor number of available structures, which can be attributed to the lack of general methods for their synthesis. The main routes to secondary 2‐amino thiols (or their disulfides) start from α‐amino acids (or their 2‐amino alcohol derivatives)3,4a,4b,6 and require a multistep sequence: N ‐alkylation,7 introduction of a sulfur nucleophile, and protection/deprotection of the amino and thiol groups. A few other methods involving secondary amines and less accessible sulfur substrates, such as thiiranes,4d,8 α,α′‐dithiodiisobutyraldehyde,9 or mercaptoethyl carbonates,10 have also been reported.…”