1. Catalytic asymmetric reactions with chiral titanium amide-alkoxide complexes
Adam R. Johnson
Department of Chemistry
Harvey Mudd College, Claremont, CA 91711

2. Modular ligand synthesis
1st generation, R’ = H
2nd generation, R’ = alkyl

3. Ligand nomenclature Can’t be made … 1st generation 2nd generation

4. Initial hydroamination results
10 mol % cat., 135˚ C
10 mol % cat., 110˚ C
All 1st generation ligands
ee’s by chiral GC of benzamide derivative
“blue” ee’s are opposite enantiomer (lower Rf found with D-ligands)
Organometallics, 2004, 4614

5. Hydroamination with bulkier L
5 mol % cat., 135˚ C
Overnight reaction, >95% completion, single product
2nd generation ligands
ee’s by chiral shift NMR using
R-O-acetylmandelic acid
“red” isomers (more downfield shift) correspond to same enantiomer as before (longer Rf by GC)

6. Benzaldehyde alkylation
-78° to room temperature overnight
Same reaction conditions for titanium complexes:
1.1 eq Et2Zn
5 mol% ligand
5 mol% Ti(OiPr)4

7. Alkylation data highlights
85-98% conversion; some reduction
R product favored with L-amino alcohols
Increase in %ee using Ti, but same enantiomer (in almost all cases)

8. Acknowledgements ACS-PRF, NSF-RUI, NSF-REU Undergraduate co-workers:
Benzaldehyde alkylation: Casey Jones (Reed, ‘05), Hanhan Li (HMC, ‘05), Joanne Redford (HMC ‘09), Sam Sobelman (HMC ‘08), Drew Kouzelos (HMC ‘07), Ryan Pakula (HMC ‘09)
Hydroamination: Amanda Hickman (HMC ‘07), Lauren Hughs (HMC ‘09)
New directions: Dianna McAnnally-Linz (Agnes Scott, ‘08), Minh Nguyen (U. La Verne, ‘08), Andrew Stewart (HMC, ‘08)