html5-img
1 / 21

Carbene Addition to C=C Bonds

Carbene Addition to C=C Bonds. Generation of carbenes. Electronic Structures of Carbenes. q ’. q. arylcarbenes cycanocarbene alkynylcarbene. :CF 2 :CCl 2 :CBr 2 :CHCO 2 R. :CH 2 ( q ' > q ). 130~150°. 100~110°. cis -olefin. cis -cyclopropane. Retentive stereochemistry. spin

lanai
Télécharger la présentation

Carbene Addition to C=C Bonds

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. Carbene Addition to C=C Bonds Generation of carbenes

  2. Electronic Structures of Carbenes q’ q arylcarbenes cycanocarbene alkynylcarbene :CF2 :CCl2 :CBr2 :CHCO2R :CH2 (q'>q) 130~150° 100~110° cis-olefin cis-cyclopropane Retentive stereochemistry

  3. spin inversion

  4. Orbital Interaction Between Carbene and Olefin > more stable asymmetrical transition state symmetrical transition state Reaction of Conjugate Dienes (cisoid) with Singlet Carbenes

  5. p–pand s–p* interactions between singlet carbenes and olefins reactive both to electron rich and deficient olefins Electrophilic nucleophilic

  6. Typical carbene reactions a-elimination Ph:

  7. a-elimination insersion Reimer-Tiemann reaction

  8. Nitrene isocyanate

  9. Electrophilic organometallic reagents the carbon-metal bond: highly polarized the carbon-halogen bond: highly polarized Simmons-Smith Reagent Carbene Metal Complexes

  10. Carbenoids: Electrophilic and Nucleophilic Properties nucleophilic carbenoid electrophilic carbenoid

  11. The first catalytic asymmetric reaction of prochiral compounds caused by soluble chiral metal complexes Nozaki, H.; Moriuchi, S.; Takaya, H., Noyori, R.Tetrahedron Lett. 1966, 5239 銅－カルベン錯体 (Simmons-Smith)

  12. 野依触媒 顕谷触媒 パーメスリン酸 シラスタティン

  13. Alkene metathesis Mechanism [2 + 2] Metal-carbene complex metallacyclobutane

  14. Evidence supporting Chauvin mechanism

  15. Addition of Radicals to C=C Bonds without peroxide Markovnikov rule: carbenium ion stability Ionic process hyperconjugation with peroxide anti-Markovnikov rule: radical stability radical process Mechanism:radical chain process

  16. Gomberg, 1900; "persistent hydrocarbon radical" "persistent hydrocarbon radical" radical with shelf-storable stability LUMO of acceptor SOMO of radical DPPH HOMO of donor capto-dative radical

  17. Some previous observations difficult to explain . fast . . minor major slow Recent findings to explain these previous issues

  18. Reasonable explanation for alternative co-polymerization: Why the reaction proceeds in such a way? Polymer)n Polymer)n+1 Favorable orbital interactions are highly specific !! LUMO LUMO SOMO SOMO HOMO HOMO

  19. Structures of Radicals

More Related