1. Stereochemical relay through oligoureas 24/02/2005

2. Synthesis Unsymmetrical Symmetrical

3. Alkyl group on meta 6.52 6.47 6.42 6.39 6.36 6.03 5.98 5.90 5.84 5.80 40°C 23°C -10°C -30°C -50°C

4. Alkyl group on meta or ortho position

5. Effect of the chiral sulfoxide The X-ray analysis confirmed that the sulfoxide control the first axis But not the entire helix

6. Effect of the chiral sulfoxide

7. 13 C i-Pr sensor The helix exists in two conformations (cis and trans) At 50°C, it seems we can clearly see the two diastereomers.

8. 13 C i-Pr sensor 23°C

9. 13 C i-Pr sensor 50°C 23°C

10. Benzylic sensor The Br-Li exchange didn’t work. The benzylic position might be the problem

11. Oligoureas connected on the ortho position Broad signals on the 1 H NMR The helix crystallised in a chiral space group as a single enantiomer