Simple, Mild and Efficient Thioacetalization and Transthioacetalization of Carbonyl Compounds and Deprotection of Thioacetals: Unique Role of Thiols in the Selectivity of Thioacetalization
Silicasupportedsodiumhydrogen sulfate (NaHSO 4 .SiO 2 ) has been employed for efficient thioacetalization and transthioacetalization of carbonyl compounds in CH 2 Cl 2 at room temperature. Selectivity of thioacetalization was dependent on the thiols used for the conversion. The same catalyst was also found to be effective for deprotection of thioacetals in CH 2 Cl 2 -H 2 O at room temperature.
Triflic Acid Catalyzed Reductive Coupling Reactions of Carbonyl Compounds with O-, S-, and N-Nucleophiles
作者:Beate A. Gellert、Nils Kahlcke、Markus Feurer、Stefanie Roth
DOI:10.1002/chem.201101819
日期:2011.10.17
Highly efficient metal‐free reductivecoupling reactions of aldehydes and ketones with a range of nucleophiles in the presence of triflic acid (1–5 mol %) as the catalyst are presented. The reactions can be performed at ambient temperature without exclusion of moisture or air. A range of symmetrical and unsymmetrical ethers were obtained by this method in high yields and short reaction times. For the
The insertion reaction of isocyanide into a C-S bond of dithioacetals is catalyzed by GaCl3 or TiCl4 to afford thioimidates containing an alpha-alkylthio group. Balanced thiophilicity of these Lewis acids is critical for efficient catalysis.