Chemoselective Dithioacetalization and Oxathioacetalization of Carbonyl Compounds Using Alumina Sulfuric Acid as Catalyst

Abstract

Carbonyl compounds have been successfully converted into their corresponding dithiolane, dithiane, and oxathiolane derivatives using a catalytic amount of alumina sulfuric acid (Al₂O₃–SO₃H) with excellent yields at room temperature in short reaction times under mild conditions. This simple method is a highly chemoselective procedure for protection of aldehydes in the presence of ketones, and the heterogeneous catalyst can be recovered and reused several times without any loss of its activity.

Keywords:

• 1,3-dithiane
• 1,3-dithiolane
• 1,3-oxathiolane
• Alumina sulfuric acid
• dithioacetalization
• heterogeneous catalyst

ACKNOWLEDGMENTS

We are thankful to the Sistan and Baluchestan University Research Council for the partial support of this research.

Notes

^a Yields refer to the pure isolated products. All known products have been reported previously in the literature and were characterized by comparison of MP, IR, ¹³C NMR, and ¹H NMR spectra with authentic samples.^[ 11-22 ^]

^b Isolated yield after five cycles with reused catalyst.

^c The reaction was performed under reflux conditions in acetonitrile as solvent.

^a GC yield using n-octane as internal standard.

^b The molar ratio of substrate 1/substrate 2/1,3-propanedithiol/catalyst was chosen 1/1/1.05/0.05 (g).