Preparation and reactions of enantiomerically pure α-functionalized Grignard reagents.
J Am Chem Soc
; 135(21): 8071-7, 2013 May 29.
Article
en En
| MEDLINE
| ID: mdl-23647498
ABSTRACT
A strategy for the generation of enantiomerically pure α-functionalized chiral Grignard reagents is presented. The approach involves the synthesis of α-alkoxy and α-amino sulfoxides in ≥991 dr and ≥991 er via asymmetric deprotonation (s-BuLi/chiral diamine) and trapping with Andersen's sulfinate (menthol derived). Subsequent sulfoxide â Mg exchange (room temperature, 1 min) and electrophilic trapping delivers a range of enantiomerically pure α-alkoxy and α-amino substituted products. Using this approach, either enantiomer of products can be accessed in 991 er from asymmetric deprotonation protocols without the use of (-)-sparteine as the chiral ligand. Two additional discoveries are noteworthy (i) for the deprotonation and trapping with Andersen's sulfinate, there is a lack of stereospecificity at sulfur due to attack of a lithiated intermediate onto the α-alkoxy and α-amino sulfoxides as they form, and (ii) the α-alkoxy-substituted Grignard reagent is configurationally stable at room temperature for 30 min.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Indicadores y Reactivos
Idioma:
En
Revista:
J Am Chem Soc
Año:
2013
Tipo del documento:
Article
País de afiliación:
Reino Unido