212 0

Gold-Catalyzed Reactions of N-O Bond Substrates

Title
Gold-Catalyzed Reactions of N-O Bond Substrates
Author
염현석
Alternative Author(s)
Yeom, Hyun Suk
Advisor(s)
신승훈
Issue Date
2009-02
Publisher
한양대학교
Degree
Master
Abstract
Part I. Gold-catalyzed reaction of N-O bond substrates: Introduction Brief history of N-O cleaving redox reaction is presented. Also, more recent examples of this redox chemistry is presented as well. Part II. Gold(I)-Catalyzed Hydroaminative Cyclization Leading to 2,5-Dihydroisoxazole Gold(I)-catalyzed intramolecular hydroamination of O-propargyl-N-Boc-hydroxylamine is reported. This process occurs via hydroamination of alkyne in 5-endo mode by N-tosyl or N-Boc amide, which in turn, derived from hydroxylamine. The present method provides a novel, catalytic, and mild approach to 2,5-dihydroisoxazole derivatives. In addition, a mechanism for the N-O cleavage as a side reaction as well as desired cyclization is proposed, which paved the way to the discovery of N-O cleaving redox reaction. Part III. Silver(I)-Catalyzed Direct Route to Isoquinoline-N-Oxides Silver trifluoromethanesulfonate efficiently catalyzes the cyclization of 2-alkynylbenzaldoxime derivatives into the corresponding isoquinoline-N-oxides. The current protocol provides a direct route to the latter skeleton under a very mild reaction condition. The usage of 'preset' oxidation state by starting from hydroxylamine derivatives obviates the problems associated with the subsequent oxidation en route to this heterocycles. Part IV. Gold-Catalyzed Waste-Free Generation and Reaction of Azomethine Ylides: Internal Redox/Dipolar Cycloaddition Cascade A novel gold-catalyzed generation of an azomethine ylide, featuring an internal redox reaction between a tethered nitrone and an alkyne under electrophilic metal catalysis is presented. Via redox reaction between nitrone and alkyne, a formal alpha-carbonyl Au-carbenoid intermediate is postulated as intermediate. The azomethine ylide that is formed is evidenced by the subsequent efficient [3+2] cycloaddition cascade that occurs in a highly efficient and diastereoselective manner. Part V. Gold-Catalyzed Isoindole Synthesis via Internal Redox: Divergent Paths Depending on the Oxime Geometry A novel approach toward isoindoles starting from the (Z)-ketoxime or nitrone via internal redox process involving N-O cleavage. We also noted an interesting chemo-divergence depending on the oxime geometry. This together with the reactivity of a variety of substrates led us to a full mechanistic scenario for this novel internal redox process of N-O bond substrates.
URI
https://repository.hanyang.ac.kr/handle/20.500.11754/144539http://hanyang.dcollection.net/common/orgView/200000410601
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > CHEMISTRY(화학과) > Theses (Master)
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE