1 / 14

Stereochemical relay through oligoureas

Stereochemical relay through oligoureas. 11/11/2004. P. M. - Is it possible to control the orientation of the helix with a chiral group A? - Is it possible to control a stereoselective reaction on B ?. Synthesis. Synthesis. Synthesis. Synthesis. Synthesis. Symmetrical oligoureas.

paulos
Download Presentation

Stereochemical relay through oligoureas

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. Stereochemical relay through oligoureas 11/11/2004 P M - Is it possible to control the orientation of the helix with a chiral group A? - Is it possible to control a stereoselective reaction on B ?

  2. Synthesis

  3. Synthesis

  4. Synthesis

  5. Synthesis

  6. Synthesis Symmetrical oligoureas

  7. Synthesis Symmetrical oligoureas

  8. Synthesis

  9. Conformation of the ureas Conformation in solution (CDCl3) and in the single cristal (Et) 5.81 ppm (i-Pr) 5.88 ppm 5.65 ppm ≈ 10 Å Two conformations at low temperature R = Et 2 conformers 50/50 à -60°C R = i-Pr 2 conformers 55/45 à -30°C

  10. With an asymmetric centre (s-Bu, racemic) 5.96 ppm M P Conformation of the ureas Conformation in solution (CDCl3) and in the single cristal Two enantiomer helices Each imposes a different conformation of a same enantiomer of the s-Bu

  11. 6.00 ppm 5.91 ppm 6.00 ppm symmetrical octaurea Conformation of the ureas Conformation in solution (CDCl3) of the oligoureas 5.91 ppm 5.91 ppm 6.03 ppm 6.02 ppm Symmetrical tetraurea unsymmetrical tetraurea

  12. Conformation of the ureas Conformation in solution (CDCl3) of the oligoureas Chiral sulfoxide 6.01 ppm 5.93 ppm 6.05 ppm 5.92 ppm 6.03 ppm 6.04 ppm

  13. ? ? A chiral i-propyl group as a sensor How to know if the sulfoxide controls the sense of the helix in solution ?

  14. Chiral i-propyl as a sensor R = CD3 de = 65% R = 13CH3 de = 81% R = CD3 87% R = 13CH3 77% R = CD3 52% R = 13CH3 68% Dynamic Thermodynamic Resolution Thayumanavan, S.; Basu, A.; Beak P. J. Am. Chem. Soc.1997, 119, 8209-8216

More Related