Cis-Selective Double Spirocyclization via Dearomatization and Isomerization under Thermodynamic Control.

Spiro compounds have been considered key scaffolds for pharmaceutical applications. Although many synthetic methods exist for monospirocycles, fewer approaches are known for dispirocycles. Here, we report a highly cis-selective method for constructing a 5/6/5-dispirocyclic structure containing pyrrolidine and γ-lactam rings with various substituents from a series of N-arylpropiolamides. The high cis-selectivity would result from isomerization under thermodynamic control. Cis- and trans-diastereomers can be in equilibrium, favoring cis-adducts.

Design, Synthesis, and Evaluation of Trivalent PROTACs Having a Functionalization Site with Controlled Orientation.

Trivalent PROTACs having a functionalization site with controlled orientation were designed, synthesized, and evaluated. Based on the X-ray structure of BRD protein degrader MZ1 (1) in complex with human VHL and BRD4BD2, we expected that the 1,2-disubstituted ethyl group near the JQ-1 moiety in MZ1 (1) could be replaced by a planar benzene tether as a platform for further functionalization. To test this hypothesis, we first designed six divalent MZ1 derivatives, 2a-c and 3a-c, by combining three variations of substitution patterns on the benzene ring (1,2-, 1,3-, and 1,4-substitution) and two variations in the number of ethylene glycol units (2 or 1). We then tested the synthesized compounds for the BRD4 degradation activity of each. As expected, we found that 1,2D-EG2-MZ1 (2a), an MZ1 derivative with 1,2-disubstituted benzene possessing two ethylene glycol units, had an activity profile similar to that of MZ1 (1). Based on the structure of 2a, we then synthesized and evaluated four isomeric trivalent MZ1 derivatives, 15a-15d, having a tert-butyl ester unit on the benzene ring as a handle for further functionalization. Among the four isomers, 1,2,5T-EG2-MZ1 (15c) retained a level of BRD4 depletion activity similar to that of 2a without inducing a measurable Hook effect, and its BRD4 depletion kinetics was the same as that of MZ1 (1). Other isomers were also shown to retain BRD4 depletion activity. Thus, the trivalent PROTACs we synthesized here may serve as efficient platforms for further applications.

Growth Inhibition of Human Breast and Prostate Cancer Cells by Cinnamic Acid Derivatives and Their Mechanism of Action.

Cancer is the leading cause of death and there is a particularly pressing need to develop effective treatments for breast and prostate cancer. In the current study, we show the inhibitory effects of cinnamic acid derivatives, including caffeic acid phenethyl ester (CAPE, 1), on the growth of breast and prostate cancer cells. Among the compounds examined, 3,4,5-trihydroxycinnamic acid decyl ester (6) showed the most potent inhibition of cancer cell growth by the induction of apoptosis. Compound 6 could be a new anti-cancer agent for use against breast and prostate cancer.

Inhibitory effects of hydroxylated cinnamoyl esters on lipid absorption and accumulation.

Obesity is a risk factor associated with several lifestyle-related diseases, for example, diabetes, high blood pressure, hyperlipidemia and cancer. Caffeic acid 2-phenylethyl ester (CAPE, 1), a naturally-occurring compound found in various plants and propolis, which exhibits anti-inflammatory, immunomodulatory and cytotoxic activities and inhibits 3T3-L1 differentiation to adipocytes. As part of our efforts to moderate lifestyle-related diseases, we synthesized analogs of 1 and studied their effects on pancreatic lipase activities, lipid absorption, and 3T3-L1 differentiation. We found that catechols 1-4 show inhibitory activities against pancreatic lipase in a dose-dependent manner in vitro. Compounds 1-3 proved to be more potent inhibitors of pancreatic lipase than 5, 6, 8, and 9, which have one hydroxyl group, respectively. Compound 7 has three aromatic hydroxyl groups and restrains greater lipase inhibitory activity than the other compounds. In addition, 7 and 3 significantly suppress a rise in blood triglyceride (TG) levels in mice given corn oil orally. Furthermore, 2 and 3 are more potent at preventing 3T3-L1 differentiation (lipid accumulation) than 1, while 7 is more potent than 3, 8, and 9 in these assays. Compounds 2, 3, and 7 inhibit lipid absorption and accumulation, with new compound 7 being the most potent. These results indicate that 7 may have potential benefits as a health agent with anti-obesity properties.

Enantioselective synthesis of (+)-penostatin E.

The first enantioselective total synthesis of penostatin E has been accomplished. Two highly efficient and diastereoselective reactions, a Hosomi-Sakurai allylation and an intramolecular Pauson-Khand reaction, were utilized for the construction of the basic carbon framework of the target molecule as the key steps. A late-stage introduction of the side chain and a successful base-promoted elimination reaction afforded an efficient synthetic route to (+)-penostatin E.

Total synthesis of debromoflustramines B and E based on the intramolecular carbamoylketene-alkene [2 + 2] cycloaddition.

Total synthesis of debromoflustramines B and E has been accomplished by using a platinum-catalyzed addition reaction of o-aminophenylboronic acid with the allene and an intramolecular carbamoylketene-alkene [2 + 2] cycloaddition for the construction of the basic carbon framework of the target alkaloids as the key steps.

Total synthesis of natural enantiomers of heliespirones A and C via the diastereoselective intramolecular Hosomi-Sakurai reaction.

A full account of the development of a novel type of the intramolecular Hosomi-Sakurai reactions of the substrates with a p-benzoquinone and an allylsilane moieties connected by an ether linkage is described. This transformation proceeds via an addition-elimination sequence and provides the products with two stereogenic centers through a 1,3(or 1,4)-asymmetric induction in good to excellent diastereoselectivities. A reasonable mechanistic possibility for the reaction, determination of the stereochemistry for the product, and scope and limitation of the transformation are also discussed. The methodology developed here can successfully be applied to the enantiocontrolled total synthesis of the natural enantiomers of (-)-heliespirone A and (+)-heliespirone C, which have been isolated from sunflower Helianthus annuus L. as allelochemicals.

Enantioselective synthesis of 8-epi-xanthatin and biological evaluation of xanthanolides and their derivatives.

An enantioselective synthesis of 8-epi-xanthatin (9) has been accomplished starting from the bicyclic lactone 3, which has been used for the synthesis of other xanthanolides, sundiversifolide (4) and diversifolide (5), through a synthetic route without the use of a selenium species. Additionally we have evaluated antimicrobial activities of five natural xanthanolides and their derivatives. Although the synthetic xanthanolides did not show any activity against methicillin-resistant Staphylococcus aureus (MRSA), some of the synthetic intermediates did exhibit moderate antimicrobial activities.

Enantiocontrolled total syntheses of breviones A, B, and C.

Enantiocontrolled total syntheses of the breviones A, B, and C have been accomplished using a highly diastereoselective oxidative coupling of an α-pyrone with a tricyclic diene prepared from an optically pure Wieland-Miescher ketone derivative through the 7-endo-trig mode of acyl radical cyclization.

Inhibitory effect of a novel thiazolidinedione derivative on hepatitis B virus entry.

The development of novel antivirals to treat hepatitis B virus (HBV) infection is still needed because currently available drugs do not completely eradicate chronic HBV in some patients. Recently, troglitazone and ciglitazone, classified among the compounds including the thiazolidinedione (TZD) moiety, were found to inhibit HBV infection, but these compounds are not clinically available. In this study, we synthesized 11 TZD derivatives, compounds 1-11, and examined the effect of each compound on HBV infection in HepG2 cells expressing NTCP (HepG2/NTCP cells). Among the derivatives, (Z)-5-((4'-(naphthalen-1-yl)-[1,1'-biphenyl]-4-yl)methylene)thiazolidine-2,4-dione (compound 6) showed the highest antiviral activity, with an IC50 value of 0.3 µM and a selectivity index (SI) of 85, but compound 6 did not affect HCV infection. Treatment with compound 6 inhibited HBV infection in primary human hepatocytes (PHHs) but did not inhibit viral replication in HepG2.2.15 cells or HBV DNA-transfected Huh7 cells. Moreover, treatment with compound 6 significantly impaired hepatitis delta virus (HDV) infection and inhibited a step in HBV particle internalization but did not inhibit attachment of the preS1 lipopeptide or viral particles to the cell surface. These findings suggest that compound 6 interferes with HBV infection via inhibition of the internalization process.

Rapid Access to Dispirocyclic Scaffolds Enabled by Diastereoselective Intramolecular Double Functionalization of Benzene Rings.

Here we describe the diastereoselective synthesis of (5r,8r)-1,9-diazadispiro[4.2.48 .25 ]tetradecatrienes via domino double spirocyclization of N-arylamide derivatives. This reaction can serve as a fast way to synthesize diazadispirocycles, which are found in the core structures of bioactive natural products. Product diversification via Suzuki-Miyaura cross coupling and application to the synthesis of 1-oxa-9-azadispiro[4.2.48 .25 ]tetradecatrienes were also conducted.

Correction to: Ceramicines M-P from Chisocheton ceramicus: isolation and structure-activity relationship study.

The article Ceramicines M-P from Chisocheton ceramicus: isolation and structure-activity relationship study.

Ceramicines M-P from Chisocheton ceramicus: isolation and structure-activity relationship study.

Ceramicines are a series of limonoids which were isolated from the bark of Malaysian Chisocheton ceramicus (Meliaceae) and show various biological activities. Ceramicine B, in particular, has been reported to show a strong lipid droplet accumulation (LDA) inhibitory activity on a mouse pre-adipocyte cell line (MC3T3-G2/PA6). With the purpose of discovering compounds with stronger activity than ceramicine B, we further investigated the constituents of C. ceramicus. As a result, from the bark of C. ceramicus four new ceramicines (ceramicines M-P, 1-4) were isolated, and their structures were determined on the basis of NMR and mass spectroscopic analyses in combination with NMR chemical shift calculations. LDA inhibitory activity of 1-4 was evaluated. Compounds 1-3 showed LDA inhibitory activity, and 3 showed better selectivity than ceramicine B while showing activity at the same order of magnitude as ceramicine B. Since 3, which possess a carbonyl group at C-7, showed better selectivity than 5, which possess a 7α-OH group, while showing activity at the same order of magnitude as 5, we also investigated the effect of the substituent at C-7 by synthesizing several derivatives and evaluating their LDA inhibitory activity. Accordingly, we confirmed the importance of the presence of a 7α-OH group to the LDA inhibitory activity.

Total synthesis of (+)-sundiversifolide.

The first, enantiocontrolled total synthesis of (+)-sundiversifolide has been accomplished using the sequential ring-closing metathesis, [3,3]-sigmatropic rearrangement, and iodolactonization for the key assembly of the cis-fused oxabicyclo[5.3.0]decene framework of the natural product. [structure: see text]

Cinnamic acid derivatives inhibit hepatitis C virus replication via the induction of oxidative stress.

Several cinnamic acid derivatives have been reported to exhibit antiviral activity. In this study, we prepared 17 synthetic cinnamic acid derivatives and screened them to identify an effective antiviral compound against hepatitis C virus (HCV). Compound 6, one of two hit compounds, suppressed the viral replications of genotypes 1b, 2a, 3a, and 4a with EC50 values of 1.5-8.1 µM and SI values of 16.2-94.2. The effect of compound 6 on the phosphorylation of Tyr705 in signal transducer and activator of transcription 3 (STAT3) was investigated because a cinnamic acid derivative AG490 was reported to suppress HCV replication and the activity of Janus kinase (JAK) 2. Compound 6 potently suppressed HCV replication, but it did not inhibit the JAK1/2-dependent phosphorylation of STAT3 Tyr705 at the same concentration. Furthermore, a pan-JAK inhibitor tofacitinib potently impaired phosphorylation of STAT3 Tyr 705, but it did not inhibit HCV replication in the replicon cells and HCV-infected cells at the same concentration, supporting the notion that the phosphorylated state of STAT3 Tyr705 is not necessarily correlated with HCV replication. The production of reactive oxygen species (ROS) was induced by treatment with compound 6, whereas N-acetyl-cysteine restored HCV replication and impaired ROS production in the replicon cells treated with compound 6. These data suggest that compound 6 inhibits HCV replication via the induction of oxidative stress.

Involvement of FKBP6 in hepatitis C virus replication.

The chaperone system is known to be exploited by viruses for their replication. In the present study, we identified the cochaperone FKBP6 as a host factor required for hepatitis C virus (HCV) replication. FKBP6 is a peptidyl prolyl cis-trans isomerase with three domains of the tetratricopeptide repeat (TPR), but lacks FK-506 binding ability. FKBP6 interacted with HCV nonstructural protein 5A (NS5A) and also formed a complex with FKBP6 itself or FKBP8, which is known to be critical for HCV replication. The Val(121) of NS5A and TPR domains of FKBP6 were responsible for the interaction between NS5A and FKBP6. FKBP6 was colocalized with NS5A, FKBP8, and double-stranded RNA in HCV-infected cells. HCV replication was completely suppressed in FKBP6-knockout hepatoma cell lines, while the expression of FKBP6 restored HCV replication in FKBP6-knockout cells. A treatment with the FKBP8 inhibitor N-(N', N'-dimethylcarboxamidomethyl)cycloheximide impaired the formation of a homo- or hetero-complex consisting of FKBP6 and/or FKBP8, and suppressed HCV replication. HCV infection promoted the expression of FKBP6, but not that of FKBP8, in cultured cells and human liver tissue. These results indicate that FKBP6 is an HCV-induced host factor that supports viral replication in cooperation with NS5A.

Diastereoselective intramolecular carbamoylketene/alkene [2 + 2] cycloaddition: enantioselective access to pyrrolidinoindoline alkaloids.

A novel and highly diastereoselective intramolecular carbamoylketene/alkene [2 + 2] cycloaddition has been developed, and the methodology was successfully applied to the enantioselective syntheses of (-)-esermethole and Takayama's intermediate for (+)-psychotrimine.

Enantioselective total syntheses of pygmaeocins B and C.

The first enantioselective total syntheses of pygmaeocins B and C have been accomplished using an efficient and highly diastereoselective intramolecular Heck cyclization for the construction of a quaternary stereogenic center and the functionalized A-ring of the natural products as the key step.

Inhibitory effects of caffeic acid phenethyl ester derivatives on replication of hepatitis C virus.

Caffeic acid phenethyl ester (CAPE) has been reported as a multifunctional compound. In this report, we tested the effect of CAPE and its derivatives on hepatitis C virus (HCV) replication in order to develop an effective anti-HCV compound. CAPE and CAPE derivatives exhibited anti-HCV activity against an HCV replicon cell line of genotype 1b with EC50 values in a range from 1.0 to 109.6 µM. Analyses of chemical structure and antiviral activity suggested that the length of the n-alkyl side chain and catechol moiety are responsible for the anti-HCV activity of these compounds. Caffeic acid n-octyl ester exhibited the highest anti-HCV activity among the tested derivatives with an EC50 value of 1.0 µM and an SI value of 63.1 by using the replicon cell line derived from genotype 1b strain Con1. Treatment with caffeic acid n-octyl ester inhibited HCV replication of genotype 2a at a similar level to that of genotype 1b irrespectively of interferon signaling. Caffeic acid n-octyl ester could synergistically enhance the anti-HCV activities of interferon-alpha 2b, daclatasvir, and VX-222, but neither telaprevir nor danoprevir. These results suggest that caffeic acid n-octyl ester is a potential candidate for novel anti-HCV chemotherapy drugs.