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Development of Transition Metal-Catalyzed Migratory Transformations

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thesis
posted on 21.10.2015, 00:00 authored by Roohollah Kazem Shiroodi
The transition metal-catalyzed 1,3-transposition reactions of different functional groups are powerful tools in organic synthesis. The first efficient and regioselective 1,3-transposition reaction of ynones (alkynyl ketones) and diynones have been developed. It was found that by employing both interrupted- and extended conjugation factors, the equilibrium between regioisomeric ynones can be selectively shifted toward the more thermodynamically stable isomer. Thus, ynones and diynones in the presence of a π-philic gold catalyst undergo a regioselective and efficient 1,3-transposition reaction to give the rearranged ynones as sole products. Transition metal-catalyzed migratory cycloisomerization reaction offers mild and selective assembly of functionalized heterocycles with diverse substitution patterns. Two complementary regioselective copper- and gold-catalyzed cycloisomerization reactions of boron-containing alkynyl epoxides toward C2- and C3-borylated furans have been developed. It was found that employment of a copper catalyst produces the C3-borylated furan via an initial 1,2-boryl migration. However, the more efficient gold-catalyzed protocol allows regiodivergent synthesis of borylated furans. Thus, a phosphite gold complex with more basic counterion strongly favors a 1,2-boryl migration during the cycloisomerization process to produce C3-borylated furans. In contrast, employment of NHC gold complex with a non-coordinating counterion affords C2-borylated furans, exclusively. One of the remarkable examples of atom- and step-economical transformation for the assembly of complex structures is the transition metal-catalyzed rearrangement of easily accessible propargylic esters and phosphates. A stereocontrolled isomerization of α-halosubstituted propargylic phosphates into valuable highly functionalized 1,3-dienes has been developed. This methodology features a double 1,3-phosphatyloxy/1,3-halogen migration relay. Stereodivergency of this method is accomplished by the choice of catalyst to selectively synthesize either (Z)- or (E)-1,3-dienes. Thus, the (Z)-dienes could be obtained exclusively in the presence of a copper catalyst, whereas the use of a gold catalyst affords the stereoisomeric (E)-dienes predominantly.

History

Advisor

Gevorgyan, Vladimir

Department

Chemistry

Degree Grantor

University of Illinois at Chicago

Degree Level

Doctoral

Committee Member

Lee, Daesung Wardrop, Duncan Mohr, Justin Alabugin, Igor

Submitted date

2015-08

Language

en

Issue date

21/10/2015