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

Abstract

The use of 2,4,4,, Nbromosuccinimide (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 yields in the presence of thiols. SCHEME 1We observed that dithioacetalization of ketones with these catalysts proceeded very smoothly and cleanly with excellent yields but with longer reaction times in comparison with aldehydes (Tables I and II).

Pot-Economy Autooxidative Condensation of 2-Aryl-2-lithio-1,3-dithianes

“…Prepared according to a modified previously reported method . Pivalaldehyde (5 mmol, 1 equiv) and N -bromosuccinimide (178 mg, 1 mmol, 0.2 equiv) were dissolved in CH 2 Cl 2 (25 mL).…”

“…34 General Procedure for Preparation of Dithioacetals 6 (Method B). On the basis of a modified previously reported method, 44 aldehyde (5 mmol, 1 equiv) and N-bromosuccinimide (178 mg, 1 mmol, 0.2 equiv) were dissolved in CH 2 Cl 2 (25 mL). The solution was then stirred under argon at rt and thiol (2.5 equiv) was added dropwise.…”

Thioacetalation and Multi-Component Thiomethylative Friedel-Crafts Arylation Using BF3SMe2

“…Advances have also been made in the field of thioacetalation, and there have been mild catalytic methods developed. ,− However, despite being the structurally simplest thioacetal derivative, methyl dithioacetals are not found in these examples, most likely due to the highly odorous nature of methanethiol. Besides methanethiol, there are also methods utilizing dimethyldislufide − to achieve methyl dithioacetals, although an unpleasant odor is associated with this reagent as well.…”

N‐Bromosuccinimide Catalyzed One‐pot and Rapid Synthesis of Acetamidobenzyl Naphthols under Mild and Solvent‐free Conditions

“…Herein, we report a new, simple, mild and effective one-pot synthesis of acetamidobenzyl naphthols by the condensation reaction of various benzaldehydes with β-naphthol and acetamide under thermal solvent-free (Method A) and microwave irradiation (Method B) conditions in the presence of N-bromosuccinimide as an effective catalyst (Eq. 1), which has been used as catalyst in some organic reactions, such as dithioacetalization and oxathioacetalization of carbonyl compounds, 21 deoxygenation of sulfoxides to thioethers, 22 conversion of aldehydes to 1,1-diacetates, 23 synthesis of 1,5-benzodiazepine derivatives 24 and acetylation of alcohols. 25…”