Stereoselective arylthiolation of dehydroalanine in the NiII coordination environment: the stereoinductor of choice

Redox‐Driven Logic Gates Based on Intramolecular Weak Interactions in Pyridyl‐Containing Diarylnitroxides

“…Other reagents are commercially available and were used as received. Bis(4‐ tert ‐butyl‐2‐(pyridin‐2‐yl)diphenylamine was synthesized according to reported procedure [44] …”

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

“…Recently, we elaborated a versatile electrochemical approach for the stereoselective functionalization of a side chain of amino acids involved in the Ni(II) chiral coordination environment [9][10][11][12][13][14][15]. A combination of redox-activity and chirality provided by the Ni-Schiff base template, supported with the protection from redox-destruction of the amino acid skeleton, makes the suggested approach a convenient route to various types of nonproteinogenic amino acids [9,10,12,13].…”

Sequential Heck Cross-Coupling and Hydrothiolation Reactions Taking Place in the Ligand Sphere of a Chiral Dehydroalanine Ni(II) Complex: Asymmetric Route to β-Aryl Substituted Cysteines

“…Given the importance in the enantiopure β-aryl-substituted cysteines, we herein report a general asymmetric route to these AAs via sequential Heck cross-coupling reaction taking place in the ligand sphere of a chiral Belokon’s dehydroalanine Ni­(II) complex ( S )-BPB-Ni-ΔAla 1 (the chiral auxiliary ( S )-BPB is ( S )-2- N -( N -benzylprolyl)­aminobenzophenone) and subsequent hydrothiolation of the obtained complex (Figure B). In this context, the functionalization and modification of the ligand sphere of a robust and bench-stable chiral Ni­(II) complex allowed us to obtain a broad range of natural and unnatural AAs in an enantioselective fashion; so, the present metal-templated approach has been proven as a simple and reliable tool for the large-scale production of enantiopure AAs on demand in academia and industry. − Although there is the precedence about the hydrothiolation of the Ni­(II) complex ( S )- 1 in literature, the synthesis of β-arylated analogues of 1 remains challenging. Furthermore, the Heck reaction with dehydroalanine derivatives is still limited to date …”

“…It is well-known that the acid-induced decomposition of corresponding Ni­(II) complexes with HCl gives α-AAs without erosion of enantiopurity (>97% ee ; see HPLC traces in the Supporting Information, Figures S29–S32). − The opposite enantiomers of cysteine derivatives ( S , R )- ent - 6a and ( S , R )- ent - 6b were also isolated in 82% and 85% yields, respectively (Scheme ). However, the decomposition of the complexes ( S , S , S )- 5f , 5i , 5g , and 5h will give the threo ( S , S )-form of cysteines, which synthesis, in fact, is also a challenging task .…”

“…However, the decomposition of the complexes ( S , S , S )- 5f , 5i , 5g , and 5h will give the threo ( S , S )-form of cysteines, which synthesis, in fact, is also a challenging task . Importantly, the chiral auxiliary was easily separated from the resulting reaction mixture by extraction or filtration in an enantiopure form as a hydrochloride salt (( S )-BPB·HCl) and can be reused for the synthesis of a new batch of the starting Ni­(II) complex 1 . − Besides, in the case of a large-scale synthesis, it is possible to recover the Ni­(II) ions as well …”