| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 103 === This thesis is composed of three parts, discussing Lewis- and Brønsted-acid-mediated intramolecular cyclization reactions of N-containing enynols and enynamides.
First, CPh3BF4-promoted cyclization of N-3-arylpropargylpyrrolidine-tethered tertiary allylic alcohols under nitrogen at room temperature produced 1-isobutenyl-2-(fluoro(phenyl)methylenylhexahydro-1H-pyrrolizidine) with excellent stereoselectivity. In this reaction, CPh3BF4 reacted as both the Lewis acid and the fluoride source for carbofluorination, providing new C(sp2)－F bond. In addition, utilizing NHTf2 afforded pyrrolizidine skeleton containing a keto functionality.
Second, In(OTf)3-catalyzed cyclization of aromatic ortho-isobutenyl-substituted enynamides under nitrogen at room temperatures afforded 2-aminoindenes. This reaction proceeded via a highly reactive keteniminium intermediate, generated in situ from ynamides and a Lewis acid, providing 2-amino-1H-indenes in high yields. Furthermore, changing the ortho-isobutenyl substitution to the ortho gem-dibromovinyl substitution, the cyclization produced the carbobromination product 1-tribromomethyl-2-amino-1H-indene in the presence of 1.2 eq. of InBr3.
Third, In(OTf)3 enabled efficient synthesis of indolizine derivatives from N-isobutenyl-2-ynamidepyrroles.
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