Intramolecular hydroamination/cyclization of aminoalkenes catalyzed by diamidobinaphthyl magnesium- and zinc-complexes

✍ Scribed by Patricia Horrillo-Martínez; Kai C. Hultzsch

• Book ID: 104096296
• Publisher: Elsevier Science
• Year: 2009
• Tongue: French
• Weight: 305 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2009.02.069

✦ Synopsis

Reaction of 2 equiv of n-Bu 2 Mg and Et 2 Zn with the chiral L-proline-derived axial chiral tetraamines (S,S,S)-1 and (R,S,S)-1 gave the chiral bimetallic complexes [M 2 {(S,S,S)-DABN(MeProline) 2 }{R} 2 ] (M=Mg, R=n-Bu ((S,S,S)-2); M=Zn, R=Et ((S,S,S)-3)) and [M 2 {(R,S,S)-DABN(MeProline) 2 }{R} 2 ] (M=Mg, R=n-Bu ((R,S,S)-2)); M=Zn, R=Et ((R,S,S)-3)). The magnesium complexes showed moderate to high catalytic activity in the intramolecular hydroamination/cyclization of aminoalkenes, though enantiomeric excess was limited to 14% ee due to protolytic ligand exchange processes. The zinc complexes were less reactive and generally required higher reaction temperatures of 60-100 °C, but achieved slightly higher enantiomeric excess of up to 29% ee.