Bromine-1,4-diazabicyclo octane

Like chlorine, bromine is used to convert secondary alcohols into ketones. A convenient way is to apply the addition product of 2 mol of bromine with l,4-diazabicyclo[2,2,2]octane (Dabco), a nonhygroscopicyellow solid, prepared by mixing carbon tetrachloride solutions of bromine and Dabco. The compound decomposes at 155-160 °C [726]. Oxidation with this addition product is carried out in acetonitrile solution at 50 °C and results in 50 and 71% yields of cyclopentanone and cyclohexanone, respectively, but very low yields of 2-pentanone [726]. 

OXIDATION, REAGENTS 1,1 -(Azodi-carbonyl)dipiperidine. Benzeneseleninic acid. Benzeneseleninic anhydride. Barium manganate. Bis 3-salicylidene-aminopropyl] aminecobalt(II). Bisltri-n-butyltin) oxide. /-Butyl hydroperoxide. /-Butyl hydroperoxide-Selenium dioxide. Caro s acid. Ceric ammonium sulfate. Chromic acid-3,5-Dimethyl-pyrazole. Chromic acid-Silica gel. 1,4-Diazabicyclo[2.2.2] octane-Bromine. 

Diazabicyclo[2.2.2]octane-Bromine complex (Dabco-2Br2). Mol. wt. 431.84, m.p. 155-160° dec., yellow, stable to light, air, water. This complex is prepared by admixture of the two compounds in CCI4. It is very slightly soluble in a variety of solvents however, in the presence of excess amine, solutions in CH3CN or CH2CI2 can be obtained. 

Benzyl ethyl sulfide allowed to react with 1,4-diazabicyclo [2.2.2] octane bromine complex in aq. 70%-acetic acid benzyl ethyl sulfoxide. Y 95%. — The reaction is very rapid. The products are completely free from sulfones. Neither cleavage of aliphatic G-S-bonds, which may occur when N-bromosuccinimide is used, nor ar. bromination, when bromine is used, has been observed. F. e., also O-labeled sulfoxides with 0-enriched water, and use of bromine complexes with pyridine and quinoline, s. S. Oae et al.. Bull. Ghem. Soc. Japan 39, 364 (1966). 

Related Reagents. Bromine-r-Butylamine Bromine Chloride Bromine-l,4-Diazabicyclo[2.2.2]octane Bromine-1,4-Dioxane Bromine-Silver(I) Oxide Bromine-Triphenyl Phosphite iV-Bromosuccinimide A7-Bromosiiccinimide-Dimethylformamide 7V-Bromosuccinimide-Dimethyl Sulfide Al-Bromosuccinimide-Sodium Azide Copper(II) Bromide Hy-drobromic Acid Mercury(II) Oxide-Bromine Phosphoms(III) Bromide Pyridinium Hydrobromide Perbromide Sodium Bromide Thallium(III) Acetate-Bromine. 

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