14 research outputs found
Total Synthesis of (Ā±)-Phomoidrideā D
Described herein is a synthetic strategy for the total synthesis of (Ā±)āphomoidrideā
D. This highly efficient and stereoselective approach provides rapid assembly of the carbocyclic core by way of a tandem phenolic oxidation/intramolecular DielsāAlder cycloaddition. A subsequent SmI2āmediated cyclization cascade delivers an isotwistane intermediate poised for a Wharton fragmentation that unveils the requisite bicyclo[4.3.1]decene skeleton and sets the stage for synthesis completion
Total Synthesis of (+)-Madindoline A and (ā)-Madindoline B, Potent, Selective Inhibitors of Interleukin 6. Determination of the Relative and Absolute Configurations
Asymmetric Total Synthesis of Neoxaline
A first
asymmetric total synthesis and determination of the absolute
configuration of neoxaline has been accomplished through the highly
stereoselective introduction of a reverse prenyl group to create a
quaternary carbon stereocenter using (ā)-3a-hydroxyfuroindoline
as a building block, construction of the indoline spiroaminal via
cautious stepwise oxidations with cyclizations from the indoline,
assembly of (<i>Z</i>)-dehydrohistidine, and photoisomerization
of unnatural (<i>Z</i>)-neoxaline to the natural (<i>E</i>)-neoxaline as the key steps
Anti-steatosis compounds from leaves of <i>Mallotus furetianus</i>
<p>There is no drug administration-approved therapy for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). In this study, eight compounds, gallic acid (<b>1</b>), methyl gallate (<b>2</b>), corilagin (<b>3</b>), 3,4,8,9,10-pentahydroxydibenzo[<i>b,d</i>]pyran-6-one (<b>4</b>), repandinin B (<b>5</b>), (Z)-3-hexenyl-Ī²-D-glucopyranoside (<b>6</b>), (+)-lyoniresinol-3Ī±-O-Ī±-L-rhamnopyranoside (<b>7</b>) and mallophenol A (<b>8</b>) were isolated from the active fractions of <i>Mallotus furetianus</i>. Three compounds, (<b>6, 7</b> and <b>8</b>) revealed potent anti-steatosis activity in the oleic acid (OA)-induced steatosis cell model, with the minimum effective concentration of 0.05 (<b>6</b>), 0.0005 (<b>7</b>) and 0.0005 (<b>8</b>) Ī¼g/mL, which were much lower than the control compound, fibrate (72.4Ā Ī¼g/mL).</p
Synthesis of Bisdesmosidic Oleanolic Acid Saponins via a Glycosylation-Deprotection Sequence under Continuous Microfluidic/Batch Conditions
We
report the first synthesis of a series of bisdesmosidic oleanolic
acid saponins using microflow reactor Comet X-01 via a continuous
flow glycosylation-batch deprotection sequence. The main results of
this study can be summarized as follows: (1) The microfluidic glycosylation
of oleanolic acid at C-28 was achieved in quantitative yield and was
applied to the synthesis of six C-28-monoglycosidic saponins. (2)
The microfluidic glycosylation of oleanolic acid at C-3 was achieved
in good yield without orthoester byproduct formation and was applied
to the synthesis of three bisdesmosidic saponins. (3) The continuous
synthesis of saponins via a microfluidic glycosylation-batch deprotection
sequence was achieved in four steps involving two purifications. Thus,
the continuous microfluidic glycosylation-deprotection process is
expected to be suitable for the preparation of a library of bisdesmosidic
oleanolic acid saponins for in vivo pharmacological studies
Total synthesis of (Ā±)-phomoidride D: A 22 year odyssey
Recent efforts in our labs. have culminated in a completed synthesis of the phomoidride D via a strategy that evolved over a 22-yr period. The evolution of this strategies will be discussed
Total synthesis of (Ā±)-phomoidride D: A 22 year odyssey
Recent efforts in our labs. have culminated in a completed synthesis of the phomoidride D via a strategy that evolved over a 22-yr period. The evolution of this strategies will be discussed
Aogacillins A and B Produced by <i>Simplicillium</i> sp. FKI-5985: New Circumventors of Arbekacin Resistance in MRSA
Aogacillins A and B, capable of overcoming arbekacin resistance in methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), were isolated from a culture broth of <i>Simplicillium</i> sp. FKI-5985. Their structures were elucidated by NMR spectroscopic studies and ECD analyses. The aogacillins possessed a novel carbon skeleton, including a Ī²-keto-Ī³-methyliden-Ī“-lactone ring connected to a 2-ethyl-6-methylcyclohexane ring by spiro conjugation
Toward the Synthesis of Phomoidride D
An efficient and highly stereoselective approach toward
the phomoidride
family of natural products is described. The carbocyclic core structure
was assembled using a tandem phenolic oxidation/DielsāAlder
cycloaddition and a tandem 5-<i>exo</i>-<i>trig</i>/5-<i>exo</i>-<i>trig</i> radical cyclization
to deliver an isotwistane intermediate that, upon a late-stage xanthate-initiated
Grob fragmentation, furnishes the requisite bicyclo[4.3.1]Ādecene
Phellilane L, Sesquiterpene Metabolite of <i>Phellinus linteus</i>: Isolation, Structure Elucidation, and Asymmetric Total Synthesis
A new cyclopropane-containing sesquiterpenoid,
phellilane L (<b>1</b>), was isolated from the medicinal mushroom <i>Phellinus
linteus</i> (āMeshimakobuā in Japanese), a member
of the Hymenochaetaceae family and a well-known fungus that is widely
used in East Asia. The planar structure of <b>1</b> was determined
on the basis of spectroscopic analysis. The authors achieved the first
total synthesis of <b>1</b>. Our protecting group-free synthesis
features a highly stereoselective one-pot synthesis involving an intermolecular
alkylation/cyclization/lactonization strategy for construction of
the key cyclopropane-Ī³-lactone intermediate. Additionally, our
synthesis determined the absolute configuration of phellilane L (<b>1</b>)