Total Synthesis of (+)-Silybin A.

We report the first total synthesis of silybin A (1). Key synthetic steps include the construction of the 1,4-benzodioxane neolignan skeleton, a modified Julia-Kocienski olefination reaction between m-nitrophenyltetrazole sulfone (m-NPT sulfone) 10 and aldehyde 21, the formation of the flavanol lignan skeleton 28 via a quinomethide intermediate under acidic conditions, and stepwise oxidation of the benzylic position of flavanol 29.

Total synthesis of (-)-domoic acid, a potent ionotropic glutamate receptor agonist and the key compound in oceanic harmful algal blooms.

The stereo-controlled total synthesis of (-)-domoic acid is described. The critical construction of the C1'-C2' -configuration was accomplished by taking advantage of an unsaturated lactam structure. The side chain fragment was introduced in the final stages of synthesis through a modified Julia-Kocieński reaction, aiming for its efficient derivatization.

Lipid Droplet Formation Is Regulated by Ser/Thr Phosphatase PPM1D via Dephosphorylation of Perilipin 1.

Hypertrophy and hyperplasia of white adipocytes induce obesity, leading to diseases such as type 2 diabetes and hypertension, and even cancer. Hypertrophy of white adipocytes is attributed to the excessive storage of the energy form of triglycerides in lipid droplets (LDs). LDs are fat storage organelles that maintain whole-body energy homeostasis.

Total Synthesis of Sophoraflavanone H and Confirmation of Its Absolute Configuration.

Sophoraflavanone H () is a polyphenol with a hybrid-type structure containing 2,3-diaryl-2,3-dihydrobenzofuran and flavanone ring moieties. This compound and related analogues are promising leads for antimicrobial and antitumor drug development. Here we describe a total synthesis of and its diastereomer.

Diastereodivergent and Regiodivergent Total Synthesis of Princepin and Isoprincepin in Both (7″,8″) and (7″,8″) Isomers.

The first total synthesis of (7″,8″)-, (7″,8″)-isomers of princepin () and (7″,8″)-, (7″,8″)-isomers of isoprincepin () was accomplished in a highly stereoselective manner via quinomethide-mediated construction of the furofuran and 1,4-benzodioxane rings. Structural confirmation methods of and were established by CD and HPLC analysis of each diastereomers with natural products.

Inhibition of lipid droplet formation by Ser/Thr protein phosphatase PPM1D inhibitor, SL-176.

Obesity is a worldwide public health problem, which is associated with various severe diseases including diabetes, hypertension, atherosclerosis, and cancer. Recent studies have revealed that combination treatment of several different compounds using low doses is effective to reduce side effects. Thus, there is a need to develop an efficient inhibitor for reducing lipid droplets with a divergent target/pathway.

Synthetic study of andrastins: stereoselective construction of the BCD-ring system.

Andrastins are meroterpenes isolated from Penicillium sp. FO-3929 that display highly potent inhibitory activities toward protein farnesyltransferase. Structurally, they possess a unique steroidal tetracyclic skeleton (the ABCD-ring) with three contiguous quaternary stereocenters on the C-ring.

Asymmetric Total Synthesis of Laurallene.

The asymmetric total synthesis of laurallene was achieved in 13 steps for the longest linear sequence with 3.3% overall yield from commercially available trans-2-pentenal. This synthesis features the highly efficient construction of a branched ether system with five oxygenated asymmetric stereocenters by the combination of a palladium-catalyzed alkoxy substitution reaction and a cobalt-catalyzed Mukaiyama oxidative cyclization.

Asymmetric Total Synthesis of Brasilicardins.

Brasilicardins, bacterial diterpenoid natural products that display highly potent immunosuppressive activity, are promising immunosuppressant drug candidates. Structurally, they can be described as hybrids of terpenoids, amino acids, and saccharides, and share a characteristic highly strained anti-syn-anti-fused perhydrophenanthrene terpenoid scaffold (ABC-ring system) with two quaternary asymmetric carbon atoms. A unified and stereoselective total synthesis of all four brasilicardins has been designed based on the strategic use of an intramolecular conjugate addition.

Inhibition of Ser/Thr phosphatase PPM1D induces neutrophil differentiation in HL-60 cells.

Protein phosphatase Magnesium-dependent 1, Delta (PPM1D) is a wild-type p53-inducible Ser/Thr phosphatase that acts as a negative regulator of the p53 tumor suppressor. Gene amplification and overexpression of PPM1D have been reported in various cancers including leukemia and neuroblastoma. Therefore, PPM1D is a promising target in cancer therapy.

Synthesis of Aryl Amine Derivatives from Benzyl Nitriles via Electrocyclization of in Situ Generated N-Silyl Ketene Imines.

The previously unexplored reactivity of N-silyl ketene imines in organic synthesis is reported. Benzyl nitriles containing an alkenyl or aryl group at the ortho position were smoothly converted into aryl amines in good yields under two sets of mild silylation conditions: (1) nonbasic conditions using TMSNTf2-iPr2NEt or (2) basic anionic conditions using lithium diisopropylamide-triisopropylsilyl chloride (LDA-TIPSCl). The reaction probably proceeds via in situ generation of an N-silyl ketene imine followed by 6π-electrocyclization and aromatization.

Novel inhibitors targeting PPM1D phosphatase potently suppress cancer cell proliferation.

Protein phosphatase magnesium-dependent 1δ (PPM1D, Wip1) is a p53 inducible serine/threonine phosphatase. PPM1D is a promising target protein in cancer therapy since overexpression, missense mutations, truncating mutations, and gene amplification of PPM1D are reported in many tumors, including breast cancer and neuroblastoma. Herein, we report that a specific inhibitor, SL-176 that can be readily synthesized in 10 steps, significantly inhibits proliferation of a breast cancer cell line overexpressing PPM1D and induces G2/M arrest and apoptosis.

Inhibition of C-terminal truncated PPM1D enhances the effect of doxorubicin on cell viability in human colorectal carcinoma cell line.

PPM1D is a p53-inducible Ser/Thr phosphatase. One of the main functions of PPM1D in normal cells is to act as a negative regulator of the p53 tumor suppressor by dephosphorylating p53 and several kinases. PPM1D is considered an oncoprotein owing to both its functions and the fact that gene amplification and overexpression of PPM1D are reported in several tumors.

Stereocontrolled synthesis of carbocyclic compounds with a quaternary carbon atom based on SN2' alkylation of γ,δ-epoxy-α,β-unsaturated ketones.

We developed a new method for stereoselective construction of an all-carbon quaternary stereogenic center on a carbocyclic ring based on regio- and stereoselective S(N)2' alkylation reactions of γ,δ-epoxy-α,β-unsaturated cyclic ketones. Treatment of the ketones, which were readily prepared in enantiomerically pure form by means of aldol condensations between 3-ethoxy-2-cycloalkenones and α,β-epoxy aldehydes, with a R(2)Zn-CuCN reagent afforded anti-S(N)2' products stereoselectively. Conversely, the corresponding syn-S(N)2' products were stereoselectively obtained through two-step transformations of the same γ,δ-epoxy-α,β-unsaturated cyclic ketones: (1) conversion of the epoxide moiety to a chlorohydrin by treatment with MgCl(2) and (2) subsequent S(N)2' substitution of the chlorohydrin with a R(2)Zn-CuCN reagent.

Total synthesis of zoanthamine alkaloids.

Zoanthamine alkaloids, isolated from organisms in the Zoanthus genus, constitute a distinctive family of marine metabolites. These molecules exhibit a broad spectrum of unique biological properties. For example, norzoanthamine inhibits interleukin-6, the key mediator of bone resorption in osteoporosis, providing a promising drug candidate for a disease that affects more than 10 million people over age 50 in the United States.

A small molecule inhibitor of p53-inducible protein phosphatase PPM1D.

PPM1D is a p53-inducible Ser/Thr protein phosphatase. PPM1D gene amplification and overexpression have been reported in a variety of human tumors, including breast cancer and neuroblastoma. Because the phosphatase activity of PPM1D is essential for its oncogenic role, PPM1D inhibitors should be viable anti-cancer agents.

Synthetic studies of the zoanthamine alkaloids: total synthesis of zoanthenol based on an isoaromatization strategy.

The total synthesis of zoanthenol, a unique aromatic member of the zoanthamine alkaloids, which has exhibited potent anti-platelet activities on human platelet aggregation, is described in full detail. The key step involves a Brønsted acid-promoted isoaromatization in the AB ring system to install the crucial aromatic ring. We have not only succeeded in the first total synthesis of zoanthenol, but also established an alternative efficient synthetic route from the commercially available norzoanthamine hydrochloride to zoanthenol.

Synthetic studies of the zoanthamine alkaloids: the total syntheses of norzoanthamine and zoanthamine.

The zoanthamine alkaloids, a type of heptacyclic marine alkaloid isolated from colonial zoanthids of the genus Zoanthus sp., have distinctive biological and pharmacological properties in addition to their unique chemical structures with stereochemical complexity. Namely, norzoanthamine (1) can suppress the loss of bone weight and strength in ovariectomized mice and has been expected as a promising candidate for a new type of antiosteoporotic drug, while zoanthamine (2) has exhibited potent inhibitory activity toward phorbol myristate-induced inflammation in addition to powerful analgesic effects.

Synthesis of the entire carbon framework of the kedarcidin chromophore aglycon.

In advanced studies directed toward the total synthesis of the kedarcidin chromophore, we have successfully achieved the late-stage installation of the nine-membered diyne ring in the presence of the highly functionalised ansamacrocyclic bridge.

Efficient construction of the kedarcidin chromophore ansamacrolide.

[Structure: see text] The streamlined assembly of the ansamacrolide framework of the kedarcidin chromophore via an efficient atropselective Sonogashira coupling step is described. To this end, two newly improved practical syntheses of the cyclopentene and diyne fragments have been developed, which feature 0.2 mol % catalytic loadings for an RCM step and i-PrMgCl/CH2I2 as a new entry to gem-disubstituted epoxides from ketones, both being applicable to 49-g scales.