ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Pinacol Synthesis in Aqueous Media

M. Mečiarová, Š. Toma, and P. Babiak

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University, SK-842 15 Bratislava

E-mail: toma@fns.uniba.sk

Abstract: Pinacol coupling of benzaldehyde in aqueous medium mediated by magnesium, zinc, iron, nickel, and tin was studied and effect of ultrasound on these reactions was examined. Magnesium-mediated pinacol coupling of various aromatic carbonyl compounds gave very good results and ultrasonic irradiation allows to shorten reaction time as well as to lower mole excess of the metal. Pinacol coupling proceeded well with zinc, too, but no reaction was observed with iron and some unexpected reaction (oxidation of benzaldehyde) was observed when nickel and tin were used as metals, respectively. The conversion of starting material as well as the proportion of a pinacol to a corresponding benzyl alcohol have strongly depended on the steric environment surrounding the carbonyl group.

Full paper in Portable Document Format: 555a302.pdf

Chemical Papers 55 (5) 302–307 (2001)