Addition of Grignard Reagents to Chiral 1,2-Bisimines: A Diasteroselective Preparation of Unsymmetrical 1,2-Diamines

✍ Scribed by Sylvain Roland; Pierre Mangeney

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 290 KB
• Volume: 2000
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(200002)2000:4<611::aid-ejoc611>3.0.co;2-9

✦ Synopsis

3,2-b]benzopyran-2-ones / (E)-2-NonenalAsymmetric synthesis / Grignard reactions / Dynamic kinetic resolution / Chiral bisimines / Unsymmetrical 1,2-diamines A diastereoselective synthesis of tert-butyl-1,2-diamines has been developed from the addition of tert-butylmagnesium chloride to the 1,2-bisimines derived from glyoxal and chiral amines such as 1-(S)-ethylphenylamine, 1-(S)-phenylpropylamine or 1-(S)-(p-chlorophenyl)ethylamine. The influence of solvent, temperature and chiral auxiliaries on the chemical reactivity and stereoselectivity has been fully studied. Evidence of a dynamic kinetic resolution during the bis-addition process of the organometallic, leading to the 1,2-di-tert-bu-Scheme 1. i) MgSO 4 , CH 2 Cl 2 ; ii) tBuMgCl, hexane, 50 °C; iii) HCO 2 NH 4 , 10% Pd(OH) 2 /C, EtOH reflux

In this paper, we wish to report these results and their application to the synthesis of new unsymmetrical 1,2-diamines.

The addition of Grignard or zinc reagents to the carbonnitrogen double bonds of the chiral 1,2-bisimine 1 [3,5] de-