Acetals: A new organocatalysis chemotype for one-pot enantioselective α-amination
Conditions are described for one-pot Br?nsted acid and organocatalysed enantioselective α-amination of acetals and associated functionalities. Of the organocatalysts screened, proline tetrazole gave the highest ee, while aqueous monochloroacetic acid proved to be the best Br?nsted acid activator regarding minimizing racemization and maximizing product yield. The reaction opens up the way for using masked carbonyl functionalities in organocatalysis.
Proline-catalysed amination reactions in cyclic carbonate solvents
Propylene carbonate is shown to be an environmentally friendly and sustainable replacement for dichloromethane and acetonitrile in proline-catalysed α-hydrazinations of aldehydes and ketones. Enantioselectivities comparable to those obtained in convention
Beattie, Christopher,North, Michael,Villuendas, Pedro
experimental part
p. 3420 - 3432
(2011/06/22)
Asymmetric α-amination of aldehydes and ketones catalyzed by tert-butoxy-l-proline
Asymmetric electrophilic α-amination of aldehydes and ketones is described using trans-3-tert-butoxy-Lproline and trans-4-tert-butoxy-L-proline as efficient catalysts. Good yields and high enantioselectivities are obtained working at 0°C or at room temper