Intramolecular hydroamination of trisubstituted aminoallenes catalyzed by titanium complexes of diaryl substituted tridentate imine-diols

Fok, Emily Y.; Show, Veronica L.; Johnson, Adam R.

doi:10.1016/j.poly.2021.115070

Cited by 3 publications

(2 citation statements)

References 62 publications

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“…Using 34b as a substrate, 37 was exclusively produced in the presence of 29a – h ( Table 9 ) as already described for the catalytic systems 21a – c and 22a – c ( Table 6 ). The ee values of a maximum of 22% are comparable to the values observed for 21a – c and 22a – c with comparable conversions ( Table 9 , entry 10) [ 90 , 97 ].…”

Section: Chiral Pool-based Catalysts For Asymmetric Hydroamination Re...supporting

confidence: 74%

“…A further modification of the earlier discussed titanium catalysts 21a – c and 22a – c ( Table 5 and Table 6 , entries 1–6), which are suitable for aminoallene ring-closing reactions, was carried out by the introduction of chiral, tridentate, dianionic imine-diol ligands at the titanium metal center, resulting in the formation of 29a – h ( 29a – e , Table 8 ; 29a – h , Table 9 ) [ 94 , 97 ]. Nevertheless, cyclization of hepta-4,5-dienylamine ( 34a ) resulted in a mixture of tetrahydropyridine 35 (40–72% yield) and pyrrolidines Z - 36 (8–17% yield) and E - 36 (17–39% yield) ( Table 8 ).…”

Section: Chiral Pool-based Catalysts For Asymmetric Hydroamination Re...mentioning

confidence: 99%

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Jumping in the Chiral Pool: Asymmetric Hydroaminations with Early Metals

2023

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The application of early-metal-based catalysts featuring natural chiral pool motifs, such as amino acids, terpenes and alkaloids, in hydroamination reactions is discussed and compared to those beyond the chiral pool. In particular, alkaline (Li), alkaline earth (Mg, Ca), rare earth (Y, La, Nd, Sm, Lu), group IV (Ti, Zr, Hf) metal-, and tantalum-based catalytic systems are described, which in recent years improved considerably and have become more practical in their usability. Additional emphasis is directed towards their catalytic performance including yields and regio- as well as stereoselectivity in comparison with the group IV and V transition metals and more widely used rare earth metal-based catalysts.

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Section: Chiral Pool-based Catalysts For Asymmetric Hydroamination Re...supporting

confidence: 74%

Section: Chiral Pool-based Catalysts For Asymmetric Hydroamination Re...mentioning

confidence: 99%

Jumping in the Chiral Pool: Asymmetric Hydroaminations with Early Metals

2023

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Prolinol‐Derived Phenoxy‐Amidine Titanium Complexes in Asymmetric Silylcyanation of Aldehydes

Vaillant‐Coindard,

Bayardon,

Rousselin

et al. 2024

Eur J Inorg Chem

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Three new tridentate phenoxy‐amidine ligands (FA) have been prepared via the ring‐opening of benzoxazole by 2‐(methylamino)ethanol, L‐prolinol and L‐diphenylprolinol. Coordination studies of these FA ligands with Ti have led to the synthesis of the complexes (L1‐L3)Ti(OiPr)2 (1a‐3a) and (L1‐L3)TiCl2(thf) (1b‐3b). The solid state structures of the dichlorido FA‐Ti complexes revealed a distorted octahedral geometry around the metallic centre provided by the FA ligand in mer‐fashion, the two residual chloro ligands in cis arrangement and a THF molecule. The chiral Ti‐FA complexes were shown to promote the asymmetric silylcyanation reaction. With benzaldehyde as substrate, the best catalyst was the dichlorido Ti complex 3b with a diphenylprolinol in the ligand backbone. It afforded the cyanhydrine with 68% conversion and 74% ee after 24 h in DCM at ‑20°C. The diisopropoxy Ti complex 3a was remarkably active with pivalaldehyde as substrate, yielding the cyanosilylated product with 99% conversion and 61% ee after only 30 min at ‑60°C.

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