Ramberg–Bäcklund reaction

In the Ramberg - Bäcklund reaction, it is a name reaction in organic chemistry, which was named after their discoverers Ludwig Ramberg and Birger Bäcklund. The reaction is a synthesis of alkenes.

Overview reaction

In the reaction of an α - halogenated sulfone is converted by reaction with a strong base to form an alkene.

Mechanism

The α - halogenated sulfones (in this case the halogen is bromine ) are treated with bases. As the base, here the hydroxide ion is used, which engages the proton and thus a carbanion. Through a nucleophilic substitution, the carbanion cleaves the halide. The result is a Episulfonintermediat. After sulfur dioxide was removed by a so-called cheletropic reaction, an olefin or alkene is formed. Occurs primarily through the less stable (Z)- alkene.

The α - halogenated sulfones can be obtained from thioethers by reaction with a halogenating agent such as N- chlorosuccinimide, followed by oxidation at the sulfur obtained. As bases and alkoxides and potassium tert-butoxide are used in an ether, in addition to the aqueous solutions of alkali metal hydroxides.

Use

Ramberg - Backlund reaction, which is used for example for the synthesis of strained unsaturated rings.