PAPER	Synthesis 2002: 0059-0062 DOI: 10.1055/s-2002-19300
© Georg Thieme Verlag Stuttgart · New York
Heteropoly Acids as Heterogeneous Catalysts for Thioacetalization and Transthioacetalization Reactions
Habib Firouzabadi*, Nasser Iranpoor*, Kamal Amani
Department of Chemistry, Shiraz University, Shiraz 71454, Iran e-Mail: firouzabadi@chem.susc.ac.ir;
Received 25 July 2001

Abstract

Heteropoly acids are effective solid catalysts for the thioacetalization of carbonyl compounds. Tungstophosphoric acid (H₃PW₁₂O₄₀), was found to be an effective and a highly selective catalyst for the thioacetalization of aldehydes, ketones and for the transthioacetalization of acetals, acylals and O,S-acetals which proceeded in excellent yields in the absence of solvent. The catalyst has also been successfully applied to the chemoselective conversion of α- or β-diketones and a β-keto ester into the corresponding dithioacetals. Sterically hindered carbonyl compounds such as camphor and benzophenone were also converted to their corresponding thioacetals in refluxing petroleum ether in 89-94% yields. Surprisingly, anthrone was reduced to anthracene in 91% yield.

Key words

carbonyl compounds - tungstophosphoric acid - heteropoly acids - thioacetalizations - transthioacetalizations