1 / 21

DIAZINES

DIAZINES. Only C-5 in pyrimidine NOT elctron def. Diazines -Reacts even less readily with electrophiles than pyridine -Reacts easily with nucleophiles (additions / substitutions) -Reacts with nucleophilic radicals (Minisci) -Reacts as dienes in DA cycloadd. (less aromatic than pyridine).

parrish
Download Presentation

DIAZINES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. DIAZINES Only C-5 in pyrimidine NOT elctron def. Diazines -Reacts even less readily with electrophiles than pyridine -Reacts easily with nucleophiles (additions / substitutions) -Reacts with nucleophilic radicals (Minisci) -Reacts as dienes in DA cycloadd. (less aromatic than pyridine)

  2. Reactions with electrophiles -Protonation -N-alkylation -Ox. to N-oxides (H2O2, peracids) -Pract. no E-fil Ar subst. (C-5 pyrimidine) -Halogenation by add. / elim. mechanisms c.f. pyridines weaker bases than pyridine

  3. Reactions with nucleophiles Addition - Rearomatization RMet: RLi, RMgX [ox]: DDQ, KMnO4 1,2- add 1,4-add Add. av NH2- (Chichibabin)

  4. Substitution on halodiazines Nucleophiles: -ammonia / amines -thiolates -malonates etc. -water / alchohols / alchoxides Leaving groups: -halogen -OMe -SO2Me rel. soft

  5. With hard Nu: Pd-cat. couplings

  6. Metallation

  7. Radical reactions (Minisci) Cycloadditions (DA)

  8. Oxydiazines Structure - Tautomerism React. with E-files More electron rich, reacts easier with E-files than diazines “OH” o/p directing

  9. React. with Nu-files Nu Ar subst More complex mech.:

  10. Undheim - Metaphase Inhibitors Metaphase Prophase Anaphase Telophase

  11. N-Deprotonation / Alkylation O-silylation / N-alkylation

  12. N-Deprotonation / Alkylation N-alkylation / C-alkylation N-alkylation / O-alkylation

  13. C-Deprotonation / Metallation Excess base Because of NH

  14. Replacement of oxygen Halogenation Oxo  thio

  15. Cycloadditions Cancer Psoralenes - Psoriasis

  16. Aminodiazines • Exists as aminodiazines (not imino…) • -NR2 electron donor: Stronger bases • -NR2 electron donor: Participates easier in E-fil Ar subst. • Diazotation reactions • Dimroth rearrangement Dimroth

  17. Synthesis of Pyridazines Carbonyl condensations Cycloadditions

  18. Synthesis of Pyrimidines Carbonyl condensations etc. Cycloadditions

  19. Bioactive Pyrimidines DNA bases Base pairs Double a-helix

  20. Anticancer comp. Antivirals HIV (RT -inhibitors) Barbiturates (old sedatives)

  21. Synthesis of Pyrazines Carbonyl condensations etc. Bioactive Pyrazines/Pyridazines: Pteridines Bacteria synthezize folic acid

More Related