Organocatalysis as a Safe Practical Method for the Stereospecific Dibromination of Unsaturated Compounds

Abstract

Organocatalytic stereospecific dibromination of a wide variety of functionalized alkenes was achieved using a stable, inexpensive halogen source, 1,3-dibromo 5,5-dimethylhydantoin, and a simple thiourea catalyst at room temperature. The presence of a tertiary amine enhanced the rate of the dibromination reaction, and yields were good in various solvents, including aqueous solvents. The procedure was extended to alkynes and aromatic rings and to dichlorination reactions by using the 1,3-dichloro hydantoin derivative.

Alkynes in Organocatalysis

“…An asymmetric bifunctional catalyst was reported by Barbas III and co-workers [19] to effect the diastereoselective di-bromination of unsaturated compounds, including prop-2ynylbenzene 15, using 1,3-dibromo-5,5-dimethylhydanthoin 16 as the halogen source (Scheme 8).…”

Organocatalysis

“…Barbas and coworkers have reported a safe and practical method for the stereospecific dibromination of alkenes (Scheme 9). 13 Organocatalytic stereospecific dibromination of a wide variety of functionalized alkenes was achieved using a stable, inexpensive halogen source, 1,3-dibromo-5,5-dimethylhydantoin 6, and a simple thiourea catalyst 7 at room temperature. The presence of a tertiary amine enhanced the rate of the dibromination reaction, and yields were good for various substrates including oxindoles in a variety of solvents, including water.…”

An Efficient Oxidation of Alcohols by Aqueous H2O2 with 1,3-Dibromo- 5,5-Dimethylhydantoin

“…1,3-Dibromo-5,5-dimethyl hydatoin (DBDMH) has been -widely used as a green sterilizing disinfectant for various water purifications due to its very cheap and very low toxic properties [ 20 ]. DBDMH with a combination of chlorinated solvents has successfully been utilized in various bromination processes including benzylic bromination [ 21 ], dibromination of functionalized alkenes [ 22 ], oxidation of thiols [ 23 ], and bromination reactions of carboxylic acids [ 24 ]. In addition, DBDMH was utilized for the oxidation of benzylic alcohols in water mediated by TEMPO/NaNO 2 [ 25 ] and cyclodextrin [ 26 ].…”