Carboxylate ion dependency in the Cu(II) catalysed asymmetric Henry reaction: Structural characterisation of a tridentate Schiff base complex containing a coordinated carboxylic acid

Küçük Resim Yok

Tarih

2017

Dergi Başlığı

Dergi ISSN

Cilt Başlığı

Yayıncı

Wiley

Erişim Hakkı

info:eu-repo/semantics/closedAccess

Özet

Six tridentate Schiff base ligands containing tertiary butyl or benzyl substituents were prepared from chiral amino alcohols and salicylaldehyde derivatives. The ligands were employed as catalysts for the Cu(II) catalysed asymmetric Henry reaction. It was discovered that when different carboxylate salts were used instead of copper acetate as the Cu(II) salt, significant changes in the enantioselectivity of the reactions were observed. Addition of Cu(OAc)(2) to the ligand prepared from salicylaldehyde and a, a-diphenyl-tert-leucinol resulted in the formation of dark green crystals. X-ray structural analysis of these crystals showed that a square planar monomeric complex had been formed rather than the expected dimer. In the structure, the copper(II) centre is bonded to the tridentate ONO ligand and an acetate ion. There is a strong hydrogen bond between the protonated alcoholic oxygen of the Schiff base ligand and the uncoordinated acetate oxygen atom. These results, taken together, indicate that the carboxylate anion may be an important part of the active intermediate when this type of copper complex is used as a catalyst in the asymmetric Henry reaction.

Açıklama

Anahtar Kelimeler

asymmetric Henry reaction, chiral copper (II) catalyst, crystal structure, intramolecular hydrogen bond, Schiff base complex

Kaynak

Applied Organometallic Chemistry

WoS Q Değeri

Q1

Scopus Q Değeri

Q2

Cilt

31

Sayı

12

Künye