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
A Simple and Practical Synthetic Protocol for Acetalisation, Thioacetalisation and Transthioacetalisation of Carbonyl Compounds under Solvent-Free Conditions
作者:Abu T. Khan、Ejabul Mondal、Subrata Ghosh、Samimul Islam
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.
equivalent, 1 was investigated in the thioacetalization reaction. Various types of aldehydes and ketones 3 were converted to the corresponding dithianes 4 in the presence of 1 in high yields (79-97%). Moreover, 1 exhibited obvious chemoselectivity betweenaldehyde and ketone in this thioacetalization reaction. A mechanism for this thioacetalization reaction is proposed.
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.