Direct Synthesis of Imines from gem-Dibromomethylaryl Derivatives:  Application to Unsymmetrically Substituted Bipyridine Frameworks

Abstract

An efficient methodology for the one-pot synthesis of imines is described starting from gem-dibromomethylaryl compounds and primary amines. The synthesis was applied to various aliphatic mono- and polyamines as well as to electron-rich anilines. The protocol was extended to 6-bromo-5'-dibromomethyl-2,2'-bipyridine to afford the corresponding imines. With n-propyl- and n-decylamine, further conversion, in three steps, to the corresponding 6-carboxy-5'-alkylaminomethyl-2,2'-bipyridine derivatives was selectively achieved, providing new tridentate ligands that may find interesting applications for the complexation of lanthanide(III) cations in their anionic or zwitterionic form.

Tris{2-[(2-aminobenzylidene)amino]ethyl}amine

“…Similar arrangements giving claw-like molecules were observed in related tertiary amines, although in less symmetric Laue groups (e.g. Weibel et al, 2002;Işıklan et al, 2010). In some instances, closely related tripodal NR 3 molecules approximate the C 3 symmetry but with R arms lying in a plane rather than forming a closed cavity (McKee et al, 2006).…”

“…For other applications, see: Zibaseresht & Hartshorn (2005); Mercs et al (2008). For similar C 3 tripodal structures, see: Weibel et al (2002); Işıklan et al (2010);McKee et al (2006); Glidewell et al (2005). The software used for analysis of the empty voids in the crystal structure was SQUEEZE in PLATON (Spek, 2009).…”

Interaction of tripodal Schiff-base ligands with silver(i): structural and solution studies

“…Crystals of the benzyl substituted ligand 1 suitable for X-ray structure analysis were grown from an n-hexane/diethyl ether mixture. Although the room temperature structure was reported in 2002, 5 it was re-determined as part of the present study at 150 K (Fig. 1) since it was of interest to re-examine the structure for the presence of potential intra-and inter-molecular interactions; this had not been carried out in the previous study.…”

“…For example, extending the structure of tren via Schiff-base condensation at each of the terminal amine groups by reaction with a range of aromatic aldehyde derivatives potentially offers a wide array of derivatives that can be matched to specific applications. 3,4 A structural study of the Schiff-base derivative 1 (Scheme 1), derived from tren and benzaldehyde confirmed the presence of a pocket in the solid state, 5 and complexation of Cu(I) with this ligand [6][7][8][9] confirms coordination of the metal ion by the four N-donor atoms with the phenyl substituents encapsulating the metal ion. This arrangement prevents further coordination to the metal centre on the exposed side 10 resulting in a tendency to form long-range intramolecular metal-hydrogen attractions.…”

Acid catalyzes the synthesis of aromatic gem-dihalides from their corresponding aromatic aldehydes

“…They can be used as starting materials for several C C coupling reactions [6][7][8][9][10] and synthesis of imines [11] as well as a parent raw material for synthesis of their corresponding amines, acids and alcohols [12,13]. Generally, ␣,␣-dihalotoluenes can be produced by catalytic or non-catalytic halogenation of toluene or halomethylation of benzene [14], however benzyl chloride is mostly the main product and trichlorobenzene is also formed.…”