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
Methyltriphenylphosphoniumtribromide acts as an efficient mild dethioketalization reagent with high selectivity for 2-phenyl and 2-vinyl 1,3-dithiannes versus 2-alkyl 1,3-dithiannes and without any secondary brominationreaction of the investigated substrates. The reaction was also successful with trimethylphenylammonium tribromide.
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.
Calcium-Catalyzed Bis-hydrothiolation of Unactivated Alkynes Providing Dithioacetals
作者:Martin Hut’ka、Tetsu Tsubogo、Shu̅ Kobayashi
DOI:10.1021/om500442u
日期:2014.10.27
Bis-hydrothiolation of alkynes providing anti-Markovnikov dithioacetals is reported. Lewis-acidic Ca(OSO2C4F9)(2) (Ca(ONf)(2)) was synthesized for the first time and was shown to be an excellent catalyst for the transformation. The reaction is highly selective and has a wide substrate scope. It was revealed that vinyl sulfides were intermediates for this transformation and that Ca(ONf)(2) efficiently catalyzed the unprecedented reactions of unactivated vinyl sulfides with thiols to afford the dithioacetals in good to high yields.
Klaveness, Jo; Undheim, Kjell, Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry, 1983, vol. 37, # 3, p. 258 - 260