Title: Transition metal-catalyzed cycloisomerizations of propargylic ureas and guanidines derived in situ from secondary propargylamines
Other Titles: Transitiemetaal-gekatalyseerde cycloisomerisaties van propargylurea en guanidines, welke in situ gegenereerd worden uit secundaire propargylamines
Authors: Pereshivko, Olga; S0221217
Issue Date: 2-Jul-2013
Abstract: Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"&#1054;&#1073;&#1099;&#1095;&#1085;&#1072;&#1103; &#1090;&#1072;&#1073;&#1083;&#1080;&#1094;&#1072;"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0pt 5.4pt 0pt 5.4pt; mso-para-margin:0pt; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}This thesis is devoted to the exploration of synthetic strategies for the generation of secondary N-alkylpropargylamines, aswell as to the study of their synthetic utility for the construction of smallheterocycles. A substantial part of this work deals with additions of secondary propargylamines tovarious heteroallennes, followed by transition metal-catalyzedcycloisomerizations. Also special attention is given to the regio- andchemoselectivity of these processes in the context of existing methodologies.The elaborated protocols rely on modern transition metal catalysis and utilizereadily available starting materials.Chapter1 serves as anintroduction to the chemistry of propargylamines in general, and secondary N-alkylpropargylamines inparticular, highlighting the A3-coupling reaction as a modernmethod for their synthesis. Several processes which are relevant to the presentstudy and which utilize secondary N-alkylpropargylaminesas starting materials, are also briefly outlined. The objectives of thecurrent research are summarized in this chapter.Chapter2 is dedicated to theelaboration of microwave-assisted Cu(I)-catalyzed coupling of a ketone, analkyne and a primary amine (KA2-coupling), providing a generalaccess to quaternary carbon-containing secondary N-alkylpropargylamines.Chapter3 describes theapplication of the above propargylamines in the Ag(I)-mediated tandem guanylation/cycloisomerizationreaction previously developed in our group, in order to access a structurallyinteresting class of heterocycles featuring a spiro-cyclic guanidine unit.Chapter4 deals with acomparative study on transition metal-catalyzed cycloisomerizations of propargylicureas derived in situ from secondarypropargylamines and tosyl isocyanate. The influence of the catalytic system onthe reaction outcome was thoroughly studied with two model examples, resultingin the establishment of two selective protocols for both O- and N-cyclizations,leading to oxazolidin-2-imines and imidazolidin-2-ones, respectively. Anattempt to rationalize the observed chemoselectivity is given.<br>Chapter5 is dedicated to theunexpected regio- and chemoselectivity of cationic gold-catalyzedcycloisomerizations of propargylic ureas derived in situ from secondary propargylamines and aryl or alkylisocyanates, providing an efficient access to the 3,4-dihydropyrimidin-2(1H)-one core.Finally,General conclusions and perspectives are highlighted.
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Molecular Design and Synthesis

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