Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/33310
Title: Development of Novel Threonine Derived Chiral Phosphines and Their Applications in Morita-Baylis-Hillman Reaction and Enantioselective [3+2] Cycloadditions
Authors: HAN XIAOYU
Keywords: Novel, threonine, chiral phosphines, enantioselective, Morita-Baylis-Hillman reaction, cycloadditions
Issue Date: 11-Jan-2012
Source: HAN XIAOYU (2012-01-11). Development of Novel Threonine Derived Chiral Phosphines and Their Applications in Morita-Baylis-Hillman Reaction and Enantioselective [3+2] Cycloadditions. ScholarBank@NUS Repository.
Abstract: The phosphine-triggered organic transformations have become a practical and powerful tool in organic chemistry. The unique reactivity of organophosphines, compared to their amine counterparts, has led to the discovery of a variety of novel reactions. This thesis describes the development of novel threonine-derived phosphine organocatalysts and their applications in Morita-Baylis-Hillman reaction and enantioselective [3+2] cycloadditions. Chapter 1 presented a brief introduction of nucleophilic phosphine catalysis and a series of phosphine-promoted enantioselective organic reactions. Selected examples illustrating recent advances in this research field were also presented. In Chapter 2, a highly enantioselective Morita-Baylis-Hillman (MBH) reaction of acrylates with aromatic aldehydes using L-threonine-derived bifunctional phosphine thiourea catalysts was described. The mechanistic aspects of the reaction were also discussed. In Chapter 3, the development of a new family of dipeptide-based chiral phosphines was presented. Such catalysts were applied to the asymmetric [3+2] cycloaddition of allenoates to a-substituted acrylates, yielding functionalized cyclopentenes with quaternary stereogenic centers in high yields and with excellent enantioselectivities. In Chapter 4, acrylamides derived from 3,5-dimethyl-1H-pyrazole were utilized in the asymmetric [3+2] cycloaddition with the allenoate catalyzed by dipeptide-derived phosphines. In Chapter 5, a highly enantioselective [3+2] annulation of aliphatic or aromatic imines with allenoates was realized by employing threonine-based dipeptidic phosphines as catalysts. Highly enantioselective 2-alkyl/aryl-substituted 3-pyrrolines could be generated in short reaction times and with low catalyst loadings. Moreover, synthetic value of this method was demonstrated by using imine?allene annulation as a key step in a concise formal synthesis of (+)-trachelanthamidine.
URI: http://scholarbank.nus.edu.sg/handle/10635/33310
Appears in Collections:Ph.D Theses (Open)

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