Tandem nucleophilic addition-Oppenauer oxidation of aromatic aldehydes to aryl ketones with triorganoaluminium reagents.

In the presence of pinacolone, the in situ prepared triorganoaluminium reagents reacted with aromatic aldehydes to give ketones in moderate to high yield. We propose that the products are formed via a tandem organoaluminium reagents addition-Oppenauer oxidation sequence.

5-{2-(4-Chloro-phen-yl)-1-[2-(4-chloro-phen-yl)-1-(3,4,5-trimeth-oxy-phen-yl)eth-oxy]eth-yl}-1,2,3-trimeth-oxy-benzene.

The title compound, C(34)H(36)Cl(2)O(7), is a by-product from the reaction of 4-chloro-benzyl-zinc chloride with 3,4,5-trimeth-oxy-benzaldehyde. In each of the two 1,2-diphenyl-ethyl moieties, the two benzene rings are arranged in a trans conformation and make C(ar)-C-C-C(ar) torsion angles of 163.64 (19) and 174.43 (18)°. The crystal structure is stabilized by van der Waals inter-actions only.

(Z)-N-(2-Chloro-benzyl-idene)aniline N-oxide.

In the title compound, C(13)H(10)ClNO, the central C-N bond has considerable double-bond character and the N-O bond indicates a formal negative charge on the O atom. The mol-ecule is stabilized by an intra-molecular C-H⋯O hydrogen bond. The geometry about the C=N bond is Z [C-C-N-O torsion angle = -4.2 (3)°] and the phenyl and benzene rings are trans-oriented around the C=N bond. The phenyl and benzene rings make a dihedral angle of 56.99 (2)°.