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Alkynal involved organocatalytic reactions

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/21096

Alkynal involved organocatalytic reactions

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dc.contributor.author Zhang, Xinshuai
dc.date.accessioned 2012-08-28T18:31:21Z
dc.date.available 2012-08-28T18:31:21Z
dc.date.issued 2012-08-28
dc.date.submitted July 2012
dc.identifier.uri http://hdl.handle.net/1928/21096
dc.description.abstract During the past twenty years, vast progress has been achieved in the field of organocatalysis. One of the fruitful areas is iminium catalysis using α, β-unsaturated aldehydes as essential reactants. Enals involved enantioselective reactions (including single-step reactions and cascade/tandem reactions) represent an enormous and fruitful research branch. In contrast, the protocols for the corresponding alkynals, even in single-step conjugate addition reactions, are extremely rare. Toward this end, my Ph. D. research work mainly focuses on the development of alkynal involved organocatalytic reactions and expands the scope of organocatalysis by uncovering new activation modes. Unlike enals, ynals with sp hybridized C≡C bonds are much less studied and the related chemistries are much less understood. Within the context, firstly, we have developed an organocatalytic regio- and stereoselective Michael additions of 1H-1, 2, 3-triazole to alkynals which afford the trisubstituted alkenes. It is found that the reaction conditions are critical for the 1- vs 2-isomers. Furthermore, we have discovered several novel asymmetric oxa-Michael-Michael/aldol and aza-Michael-aldol(-aromatization) reaction sequences initiated by the Michael addition to alkynals. Notably, an unprecedented chiral iminium-allenamine cascade is disclosed for the first time. Significantly, these processes serve as efficient and straightforward entries to biologically significant chiral 4H-chromenes, polysubstituted quinolines and chiral 1,4-dihydroquinolines with excellent yield and enantioselectivity, as well as broad substrate compatibility. The proposed iminium-allenamine activation mode adds a new domain in the field of organocatalytic enantioselective cascade reactions. Finally, unprecedented organocatalytic 1,6-conjugated addition to yenals, an unmet challenging problem in organic synthesis, also has been realized. en_US
dc.language.iso en_US en_US
dc.subject alkynal en_US
dc.subject Organocatalysis en_US
dc.subject Iminium-Allenamine en_US
dc.subject.lcsh Enantioselective catalysis.
dc.subject.lcsh Imines.
dc.subject.lcsh Aldehydes.
dc.title Alkynal involved organocatalytic reactions en_US
dc.type Dissertation en_US
dc.description.degree Chemistry en_US
dc.description.level Doctoral en_US
dc.description.department University of New Mexico. Dept. of Chemistry en_US
dc.description.advisor Wang, Wei
dc.description.committee-member Mariano, Patrick
dc.description.committee-member Guo, Hua
dc.description.committee-member Feng, Changjian


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