Coupling reactions 2

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Coupling reactions 2

  1. 1. COUPLINGREACTIONS
  2. 2. Coupling Reactions  Coupling reactions occur between organometallic with organic halide with the aid of a metal containing catalyst.  Coupling reactions can be divided into two main classes, cross couplings in which two different molecules react to form one new molecule.  The other type of coupling is homocoupling, in this reaction two similar molecules coupling together to form a new molecule.
  3. 3. Main features  Common metal used in this field is Pd, in addition to Zn, Ni, Cu, B, and Sn.  Most of coupling reactions are air and water sensitive ??  But, some coupling reactions can be carried out in aqueous solutions.
  4. 4. Some thing about Palladium
  5. 5. Important coupling reactions Reaction Year Reactant 1 Reactant 2 Catalyst Kumada 1972 R-MgBr RX Pd or Ni Heck 1972 Alkene RX Pd Sonogashira 1973 Alkyne RX Pd or Cu Nigishi 1977 R-Zn-X RX Pd or Ni Stille 1977 R-Sn-R3` RX Pd Suzuki 1979 R-B(OR)2 RX Pd Hyiama 1988 R-Si-R3 RX Pd Buchwald-Hartwig 1994 R2-N-R RX Pd
  6. 6. Kumada coupling reaction  Cross coupling between aryl or alkyl Grignard with aryl or vinyl halocarbon.  The first Pd or Ni catalysed coupling reaction
  7. 7. Kumada coupling
  8. 8. Kumada coupling
  9. 9. Heck coupling  Pdcatalyzed coupling between aryl or vinyl halides with activated alkene in basic media.
  10. 10. Heck coupling
  11. 11. Sonogashira coupling  Terminal alkynes with aryl or vinyl halides (triflate).  Pd as a catalyst, Cu as co-catalyst and an amine as a base.
  12. 12. Sonogashira coupling
  13. 13. Sonogashira coupling
  14. 14. Nigishi coupling  Pd or Ni catalyzed coupling organozinc compounds with aryl, vinyl, benzyl halids.
  15. 15. Nigishi coupling
  16. 16. Stille coupling  Using tin (stannes) alkyl compounds, wide range of R groups, but?????  Less polar, more toxic???
  17. 17. Stille coupling
  18. 18. Suzuki coupling Usingboronic acids or esters B(OR)3 . Needs base to activate boron species
  19. 19. Suzuki coupling
  20. 20. Suzuki coupling
  21. 21. Hyiama coupling  Organosilanes (Si), with organohalids.  Needs base or fluoride ion to activate  Fluorinated, methoxyleted silanes more reactive than alkyl ones.
  22. 22. Hyiama coupling
  23. 23. Buchwald-Hartwig coupling  Pd catalyzed synthesis of aryl secondry or tertiary amines.  Using primary or secondry amins and aryl halides (or triflates)
  24. 24. Buchwald-Hartwig coupling
  25. 25. Buchwald-Hartwig coupling
  26. 26. Fukuyama Coupling*  Pd catalyzed coupling of organozinc with thioesters to form ketones.

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