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C-C bond forming reactions Known C-C bond forming reactions PowerPoint Presentation
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C-C bond forming reactions Known C-C bond forming reactions

C-C bond forming reactions Known C-C bond forming reactions

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C-C bond forming reactions Known C-C bond forming reactions

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  1. C-C bond forming reactions Known C-C bond forming reactions (New C-C bond forming reactions in KJM3200) Organometallic coupling C-C bond forming reactions Protecting groups in organic synthesis

  2. Addition to carbonyl groups

  3. See also lab ex 6

  4. Conjugate addition Nucleophilic addition to alkenes (chapt. 23) Conjugate add., 1,4-add., Michael add.

  5. Alkylation a to C=O (also for instance RR2CHCN) (new)

  6. Alkylation of alkynes Electrophilic aromatic substitution

  7. Cycloadditions (chapt. 30, in the end of this course) Rearrangements

  8. C-C Bond Formation - Organometallic Coupling Reactions (McM 10.9, Lab ex 10)

  9. Grignard reagents and Organolithium reagents Reacts with carbonyls Strong bases RMgX or RLi does not react well with alkyl halides in substitutions

  10. Organocuprates (McM 10.9) Gilman reagent Dialkylcuprate (R: alkyl, alkenyl, alkynyl, aryl) Participate in substitution with alkylhalides (Cl, Br, I) Mech. see next slide

  11. Not SN1 or SN2 Also reaction with alkenyl halides and arylhalides (sp2)

  12. Palladium catalyzed coupling reactions (Lab ex. 10) R’-Met: R’ZnX - Negishi coupling - Esp. good for R’ = alkyl, R’ZnX generated in situ R’SnBu3 / R’SnMe3 - Stille coupling -R’ (alkynyl) aryl, alkenyl, organotin comp. tox R’SnBu3 / R’SnMe3 stable R’B(OH)2 / R’B(OR)2- Suzuki coupling - R’ (alkynyl) aryl, alkenyl, Green react. R’B(OH)2 / R’B(OR)2 relatively stable react. requires base R’MgX - Kumada coupling Less reactive, often Ni-cat. (less stable than Pd-cat)

  13. General mechanism Alkenyl or aryl halides Pd complex from aklyl halides unstable Met: -ZnX, -B(OH)2, -SnR3 (-MgX) Alkynyl, alkenyl, aryl, alkyl reacts (depending on the metal used)

  14. The Suzuki reaction

  15. Special cases - No preformed R’Met Coupling on alkynes - Sonogashira coupling Coupling on alkenes - Heck coupling (Somewhat diff. mech.)

  16. Why difficult to couple alkyl halides

  17. Protecting groups (PG) in organic synthesis (McM 17.9)

  18. Examples Protection of ROH (McM 17.9)

  19. Other ex. of ROH protecting groups (not mentioned in McM) esters also for prot. of acids

  20. Protection of aldehydes / ketones (McM 19.11) • Two extra steps • The protecting group curse