Reducion Duplicative d'Acetals Derivs d'Aldehydes Aromatiques par la Combinaison Bimetallique Aluminium/Plomb: Preparation de 1,2-Diaryl- 1,2-Dimethoxyethanes

Dhimane, H.; Tanaka, H.; Torii, S. Bull. Soc. Chim. Fr. 1990, 127, 283.

Various bimetal redox systems Al/MX_n(M=V, Nb, Co, Hg, Ge, Sn, Pb and Bi) were found efficient electron sources to promote the reductive coupling of benzaldehyde dimethylacetal into 1,2-diphenyl-1,2-dimethoxyethane 2a. Among combinations the bimetal system Al/PbBr₂ gives the best results with dimethylacetals derived from aromatic aldehydes leading to the corresponding 1,2-diaryl-1,2-dimethoxyethanes 2. On the other hand, the reductive dimerization of acetals derived from aliphatic aldehydes does not take place with the previous bimetal redox system Al/MX_n, meanwhile under the same conditions the mixed acetals (a-methoxycarbamates) 4a,b lead to the corresponding carbamates 5a,b by hydrogenolysis of the carbonoxygen bond (N-C-OMe).