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Description:
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The development of new asymmetric synthetic methodologies is both challenging and crucial for modern organic synthesis . The amino functionalization of olefins , especially the ¦Á ,¦Â -unsatuarated carbonyl system , gives very important building blocks for organic and pharmaceutical synthesis . The asymmetric halo aldol reaction can greatly extend the scope of the classic aldol reaction , and can serve as a powerful tool for asymmetric carbon -carbon bond formations .
This dissertation presents a versatile system for the electrophilic amino functionalization of the ¦Á ,¦Â -unsatuarated carbonyl compounds . By changing reaction conditions , the reaction can result in four different and important products : vicinal chloroamines , N -protected aziridines , diamines and ¦Á ,¦Â -dehydroamino acid derivatives . All of these transformations showed good chemical yields and excellent regio - and stereoselectivities . It is very easy to perform these reactions economically in large scale .
Several new asymmetric halo aldol reactions have been achieved in this dissertation . For the chiral auxiliary -controlled asymmetric halo aldol reaction , menthyl and Evans oxazolidinone were used as the chiral auxiliaries and Et2AlI /MgI2 were used as the Lewis Acid catalysts . The reagent -controlled protocol take advantage of the combination of chiral Salen and Et2AlI as the chiral reagent . Finally , an efficient asymmetric catalytic halo aldol reaction was established , in which a catalytic amount of chiral aluminum complex was used as the catalyst . All of these approaches resulted in good chemical yields and moderate to good diastereomeric and enantiomeric excesses . |