10.1007/s11178-008-1012-0

Abstract

Substituted o-cycloalkylanilines reacted with 2-hydroxynaphthalene-1-carbaldehyde in methanol in the presence of formic acid to give the corresponding Schiff bases as ligands for the synthesis of titanium(IV) complexes. * For communication VII, see [1].Matsui et al. [2] showed that titanium and zirconium chelates with salicylaldehyde imine ligands exhibit a high catalytic activity in polymerization of olefins and revealed a strong dependence of their catalytic activity on the structure of the aldehyde and amine fragments. Variation of substituents in the ligand could change the polymerization mechanism so that a broad spectrum of polyolefins with versatile parameters could be obtained [3]. It should be noted that ligands for the above complexes were synthesized mainly from substituted salicylaldehydes. Complexes with ligands based on naphthalenecarbaldehydes having a hydroxy group in the ortho position with respect to the aldehyde group were described in patent [4], but no data on their catalytic activity were given.While searching for new catalysts active at elevated temperature [5] we followed an approach based on introduction of a cycloalkyl group into the ortho position of an arene ring [6]. Such structural modification turned out to be successful for 2,6-bis(aryliminoalkyl)pyridine iron chloride complexes and 1,2-bis(arylimino)acenaphthene nickel bromide complexes. Catalysts on the basis of these complexes showed high efficiency over extended temperature range [7].In the present work we applied the above approach to the synthesis of Schiff bases from 2-hydroxynaphthalene-1-carbaldehyde and substituted anilines having a cyclopentyl, cyclohexyl, or cyclooctyl group in the ortho position with a view to make such compounds R = R′ = H (a), Me (c); R = Me, R′ = H (b); R = cyclo-C 4 H 7 (CH 2 ) n , R′ = H (d); II, V, n = 1; III, VI, n = 2; IV, VII, n = 4. CHO OH I + R NH 2 R' ( ) n IIa-IId, IIIa-IIId, IVa-IVc MeOH, HCOOH, 65°C OH N R' R ( ) n Va-Vd, VIa-VId, VIIa-VIIc Scheme 1.