LEADER 00000nam 2200337 4500
001 AAI3225509
005 20080111103758.5
008 080111s2006 eng d
020 9780542799846
035 (UMI)AAI3225509
040 UMI|cUMI
100 1 Mulrooney, Carol A
245 10 Substrate scope of the asymmetric biaryl coupling
reaction. Asymmetric synthesis of a perylenequinone.
Progress toward the synthesis of cercosporin
300 278 p
500 Source: Dissertation Abstracts International, Volume: 67-
07, Section: B, page: 3806
500 Adviser: Marisa C. Kozlowski
502 Thesis (Ph.D.)--University of Pennsylvania, 2006
520 The Kozlowski group has developed an asymmetric copper-
catalyzed oxidative biaryl coupling reaction using a novel
1,5-diaza-cis-decalin ligand. This reaction gives good
yields and enantioselectivities for a number of 3-
substituted 2-naphthols to yield new BINOL derivatives. A
substrate scope has been explored yielding insight into
the utility and reaction mechanism. Compounds that have
chelating groups in the 3-position are optimal for biaryl
coupling. A series of 3-sulfone-2-naphthols is described
for this reaction. The geometry and the electron-
withdrawing character of the substituent are important for
optimal coupling. The oxidation potential of the naphthol
is important for oxidation, electron-donating substituents
placed in the system have an effect on the yield and
enantioselectivity of the reaction.*
520 To explore the utility of the reaction further toward the
synthesis of natural products and their derivatives, a
series of highly substituted 2-naphthols was synthesized
in order to explore the synthesis of perylenequinone
natural products. Building on previously established
successful biaryl couplings of highly substituted 2-
naphthols, a model system was developed toward the
synthesis of a perylenequinone derivative with the axial
chirality as the only chiral element. Initial progress via
an ortho-quinone led to racemized product. A nucleophilic
aromatic substitution reaction was utilized to provide the
oxygenation needed to transform the highly substituted
biaryl 47 to a chiral perylenequinone.*
520 Steps toward the synthesis of the natural product
cercosporin were then developed. A mild decarboxylation
reaction was employed to remove the methyl esters that
were necessary for asymmetric biaryl coupling but not
present in the natural product. An allyl group was
introduced in the C7 position that would be later used to
introduce the chiral alcohols in the side chains. The 7-
membered ring present in cercosporin was introduced by C5/
C5' hydroxylation, then a selective deprotection strategy
followed by methylenation yielded intermediate 124.
Initial studies toward the introduction of the C7/C7'
chiral secondary alcohols proved disappointing. A survey
of chiral reductions was initiated on a model system with
moderate enantioselectivities achieved. Future plans are
proposed to introduce the chiral secondary alcohol via
reduction of a ketone with various chiral ligands.*
520 *Please refer to dissertation for diagrams
590 School code: 0175
590 DDC
650 4 Chemistry, Organic
690 0490
710 2 University of Pennsylvania
773 0 |tDissertation Abstracts International|g67-07B
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