Trichloroisocyanuric Acid, as an Industrial Chemical, Promotes Transthioacetalization of Diacetals of 2,2-Bis (Hydroxymethyl)-1,3-propanediol and Cleavage of Thioacetals
Trichloroisocyanuric acid has been used as a mild, efficient, and new catalyst for transthioacetalization of diacetals of 2,2-bis (hydroxymethyl)-1,3-propanediol in CH 2 Cl 2 at room temperature. A clean, easy, and general method for efficientdeprotection of thioacetals to their corresponding carbonyl compounds using trichloroisocyanuric acid/silica gel and water system also is described.
2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO), N-Bromosuccinimide (NBS) and Bromine as Efficient Catalysts for Dithioacetalization and Oxathioacetalization of Carbonyl Compounds and Transdithioacetalization Reactions
作者:Nasser Iranpoor、Habib Firouzabadi、Hamid Reza Shaterian、M. A. Zolfigol
DOI:10.1080/10426500211712
日期:2002.5.1
6-tetrabromo-2,5-cyclohexadienone (TABCO), N-bromosuccinimide (NBS), and bromine as efficient catalysts for conversion of carbonyl compounds to their cyclic and acyclic dithioacetals and 1,3-oxathiolanes under mild reaction conditions are described. These catalysts are also used for efficient transdithioacetalization of acetals, diacetals, ketals, acylals, enamines, hydrazones, and oximes with high
2,6-Dicarboxypyridinium Chlorochromate. An Efficient and Selective Reagent for the Mild Deprotection of Acetals, Thioacetals, and 1,1-Diacetates to Carbonyl Compounds
chlorochromate (2,6- DCPCC ) was found to be an efficientreagent for the conversion of acetals, thioacetals, and 1,1-diacetates to their corresponding carbonyl compounds under neutral and anhydrous conditions in good to excellent yields. Selectivedeprotection of acetals or 1,1-diacetates in the presence of thioacetals at room temperature is also observed with this reagent.
Two novel, non-thiolic, odorless dithiol equivalents, α,α-diacetyl cyclic ketene dithioacetals 2a and 2b, had been developed. A range of carbonyl compounds 3 were converted into corresponding dithioacetals, dithianes 4 and dithiolanes 5, in high yields (up to 99%) in the presence of 2a or 2b. Moreover, 2a and 2b show high chemoselectivity between aldehyde and ketone in thioacetalization.
Entirely Solvent-Free Procedure for the Synthesis of Distillable 1,3-Dithianes Using Lithium Tetrafluoroborate as a Reusable Catalyst
作者:Tsuneo Sato、Kiyoshi Kazahaya、Shinya Tsuji
DOI:10.1055/s-2004-829084
日期:——
Treatment of various types of aldehydes and ketones with 1,3-propanedithiol in the presence of a catalytic amount of lithium tetrafluoroborate at 25 °C under solvent-free conditions followed by direct purification by distillation of the resulting mixture affords the corresponding 1,3-dithianes in good to excellent yields. Chemoselective protection of keto aldehydes is also successfully achieved over the catalyst. The catalyst can be recovered and reused.