Suzuki Reaction.pptx

Suzuki Reaction and its Mechanism, Akira Suzuki, Trans metalation, Reductive Elimination, Merits, Green synthesis

1. Suzuki Reaction and its Mechanism Hajira Mahmood Ph.D. CHEMISTRY

2. Suzuki Reaction It is an organic reaction, classified as a cross-coupling reaction, where the coupling partners are a boronic acid and an organohalide. The catalyst being used is a palladium complex. The Suzuki Reaction is an important type of coupling reaction, a designation that encompasses a variety of processes that combine (or “couple”) two hydrocarbon fragments with the aid of a catalyst.  The reaction can conjoin a variety of aryl halides and alkenyl halides with alkenyl boranes and aryl boronic acids.   Commonly referred to as the Suzuki cross-coupling An important method of synthesizing many styrene, alkenes, and biphenyls.

3. Akira Suzuki  Japanese chemist   Nobel Prize in 2010 first published the Suzuki reaction, the organic reaction of an aryl- or vinyl-boronic acid with an aryl- or vinyl-halide catalyzed by a palladium complex, Reported in 1979 by Akira Suzuki and N. Miyaura .

4. Mechanism of Suzuki Reaction Palladium catalyzed cross-coupling reactions, between an organic halide and an organometallic reagent, that forge carbon-carbon bonds constitute one of the central pillars of modern-day organic synthesis.  Three sequential mechanistic events define the general catalytic cycle 1. oxidative addition of the organic halide to palladium (0) to form a palladium (II) complex 2. trans metalation  i.e. transfer of the organic portion of the organometallic reagent to the palladium (II) center.  3.  reductive elimination to form the new carbon-carbon bond and regenerate palladium (0) catalyst.

5. Mechanism of Suzuki Reaction

6. Oxidative Addition   The rate determining step of the catalytic cycle Couples the palladium catalyst to the alkyl halide which gives rise to the organopalladium complex  The complex is initially in the cis conformation but isomerizes to the trans conformation Stereochemistry with vinyl halides are retained but inversion of stereochemistry occurs with allylic or benzylic halide

7. Trans metalation The role of base is to activate the boron-containing reagent, and facilitate the formation of R1PdOR from R1Pd-X.   Reaction does not occur in the absence of base. 

8. Reductive Elimination T his final step gives the desired product and it also regenerates the palladium catalyst so that it can participate again in the catalytic cycle (I.e. making more products).   Require the complex to revert to the cis conformation before reductive elimination can occur

9. Merits  Mild Reaction Conditions   Availability of common boronic acids   Inorganic by-products are easily removed from reaction mixture.   Stereoselective   Less toxic than other competitive methods, ( ie . Boronic acids are environmentally safer and less toxic than organostannanes )   Reaction will take place in the presence of other functional groups ( ie . protecting group is not always necessary)   Relatively cheap reagents, easy to prepare, and GREEN!