Solvent-Free Synthesis of Salen Ligands and Pd(II)– and Cu(II)–Salen Complexes: Their Use in the Oxidation of α-Tetralones to α-Naphthols

Abstract

Racemic trans-cyclohexane-1,2-diamine was allowed to react with eleven aldehydes with different patterns of substitution at the aromatic ring, in the absence of solvent, by manually milling the reagents. The corresponding imines were obtained in moderated to high chemical yields, in only 10 minutes of reaction. A one-pot, two-step preparation of stable complexes of selected imines with Pd(OAc)2 and Cu(OAc)2 and the use of these complexes as catalysts in the aromatiz­ation of methyl 1-oxo-1,2,3,4-tetrahydronaphthalene-2-carboxylate to the corresponding methyl 1-hydroxynaphthalene-2-carboxylates, is also reported.