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The development of small molecule inhibitors of programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) has drawn research interest for the treatment of cancer. Recently, we reported the discovery of a novel dimeric core small molecule PD-1/PD-L1 inhibitor. In an effort to discover more potent inhibitors, we further explored the dimeric core scaffold. Our investigations of the structure-activity-relationship revealed that introduction of lipophilic substituents onto one of the di-alkoxylated phenyl rings improved binding affinities to PD-L1, and inhibitory activities of PD-1/PD-L1 in cellular assays. Furthermore, conversion of the ether linker part to an olefin linker not only improved binding affinity but also led to slow dissociation binding kinetics. We also explored more potent, as well as downsized, scaffolds. Compounds bearing a linear chain in place of one of the di-alkoxylated phenyl rings exhibited good binding affinity with improved ligand efficiency (LE). Representative compounds demonstrated potent inhibitory activities of PD-1/PD-L1 in the submicromolar range in cellular assays as well as cellular function in the mixed lymphocyte reaction (MLR) assay with efficacy comparable to anti-PD-1 antibody. Our results provide applicable information for the design of more potent inhibitors targeting PD-1/PD-L1 pathway.

The development of small molecule inhibitors of PD-1/PD-L1 is eagerly anticipated for treatment of cancer. We focused on the symmetry of the ternary complex structure of reported small molecule ligands and hPD-L1 homodimers, and designed partially- or fully-symmetric compounds for more potent inhibitors. The design of the new compounds was guided by our hypothesis that the designed symmetric compound would induce a flip of sidechain of ATyr56 protein residue to form a new cavity. The designed compound 4 exhibited substantially increased binding affinity to hPD-L1, as well as PD-1/PD-L1 inhibitory activity in physiological conditions. Compound 4 also showed a dose-dependent increase in IFN-γ secretion levels in a mixed lymphocyte reaction assay. These results not only indicate the feasibility of targeting the PD-1/PD-L1 pathway with small molecules, but illustrate the applicability of the symmetry-based ligand design as an attractive methodology for targeting protein-protein interaction stabilizers.

Following the discovery of JTK-109 ( 1 ) as a potent inhibitor of hepatitis C virus NS5B RNA-dependent RNA polymerase, [(a) Hirashima, S.; Suzuki, T.; Ishida, T.; Noji, S.; Yata, S.; Ando, I.; Komatsu, M.; Ikeda, S.; Hashimoto, H. J. Med. Chem. 2006 , 49 , 4721. (b) Hashimoto, H.; Mizutani, K.; Yoshida, A. Int. Patent Appl. WO 01/47883, 2001.] further studies toward the improvement of the cellular potency have been performed. A greater than 40-fold improvement was achieved through replacing the biphenyl moiety with a 2-morpholinophenyl group and the benzimidazole ring with the tetracyclic scaffold to afford compound 7 with an excellent replicon potency (EC 50 = 7.6 nM).

Effects of crosslinks on plastic strain recovery in epoxy glass was studied by means of thermally stimulated strain recovery (TSSR) and differential scanning calorimetry (DSC) techniques. Two types of samples were prepared from bisphenol-A type epoxide monomer: one had a crosslinked structure cured by 4,4′-diaminodiphenylmethane and the other had a linear uncrosslinked structure polymerized by aniline. Both specimens were compressed first in the rubbery state and subsequently compressed further in the glassy state. After compressed in the glassy state, the specimens were subjected to the TSSR and the DSC measurements. The TSSR results indicated that the amount of plastic strain recovering at temperatures below the glass transition temperature T g was larger for the crosslinked sample than for the linear sample. On the other hand, the DSC results indicated that the amount of exothermic heat flow at temperatures below T g was less for the crosslinked sample than for the linear sample. These results presumably indicate that, for the crosslinked epoxy glass deformed in the glassy state, glass-like strain recovers quite cooperatively with rubber-like strain at temperatures below T g , in contrast to independent recovery of these strains in the linear epoxy glass.

The inundation process caused by the penetration of swells and long-period waves into the mouth was investigated through field observation and numerical analysis, taking the Segami River flowing into Hitachi Port in Ibaraki Prefecture as the example. Due to the river improvement for flood control, the riverbed was deepened, enhancing vulnerability against wave penetration. The effectiveness of the plan constructing a detached breakwater off the river mouth and a reduction pond in the river was confirmed by the numerical analysis.

The Cu(I)-catalyzed boration of an α,β-enone using a diboron is described. Combination of a Cu(I) salt and tributylphosphine is an effective catalyst system, though the individual use of Cu(I) and tributylphosphine is not active for the reaction.

Highly stereoselective metathesis reactions between optically active silyl compounds and copper(I) salts in 1,3-dimethyl-2-imidazolidinone (DMI) are reported. The substitution reaction of (+)-α-naphthylphenylmethylsilane with a mixture of lithium tert-butoxide and copper(I) salt smoothly proceeded in DMI to give the corresponding silyl ether with a high degree of retention of the configuration in a quantitative yield. The use of DMI as a solvent and the presence of a chloride ion are necessary for this reaction. An optically active alkynylsilane also reacted with the mixed reagent to afford the corresponding silyl ether. A mechanism of oxidative addition of the hydrosilane and reductive elimination of the silyl ether on copper is proposed.

A variety of 6-substituted 3,5-diaryl-1,2,4-triazines were synthesized. These diaryltriazines, which incorporate a triazine nucleus substituted by two aryl moieties, comprise a new class of bleaching herbicides. The structure-activity relationships were proved by introducing a variety of substituents into the triazine and/or two aryl groups. The results indicated very specific structure requirements for herbicidal activity. Highest activity was seen with compounds that contain three substituents: a chlorine group at a meta position of an aryl moiety at the triazine 5-position, a fluorine group at the meta or para position of the other aryl moiety at the 3-position, and an ethylamino group at the 6-position of the triazine nucleus

The palladium-catalyzed reaction of 2-alkynylanilines and 2-alkynylphenols in the presence of carbon monoxide and methanol under basic conditions gave the sequential cyclization / carbonylation products, methyl 2-substituted indole and benzo[b]-furan-3-carboxylates. Similar reaction of 2-alkynylbenzamides gave 3-alkylidenisoindole derivatives.

The oxidative addition of active zinc to iodo- and bromo-substituted π-deficient heteroarenes such as pyridine, pyrimidine, and quinoline gave the corresponding heteroarylzinc halides which were transformed to the arylated and benzoylated derivatives by palladium-catalyzed reaction.

The palladium-catalyzed cross-coupling reaction of aryl iodides with 3,3,3-triethoxy-1-propyne gave 1-aryl-3,3,3-triethoxy-1-propynes which were converted to the corresponding ethyl arylpropiolates. The arylpropiolates were also synthesized from the cross-coupling reactions of aryl iodides with 2-ethoxycarbonyl-1-ethynylzinc chloride or ethyl (tributylstannyl)propiolate, but the reactions were not generally applicable

1,3-Dipolar cycloaddition reaction of diazomethane and ethyl diazoacetate with tributylstannyl-acetylenes occurred regioselectively to afford the corresponding 3(5)-tributylstannylpyrazoles. The cycloaddition reaction of 3-phenylsydnone with the stannylacetylenes proceeded also regioselectively, and 3-tributylstannyl-1-phenylpyrazoles were isolated. 4-Tributylstannyl- and 5-tributylstannyl-1-phenylpyrazole were prepared by the stannylation of 4-lithio- and 5-lithio-1-phenylpyrazoles with tributylstannyl chloride. Iodination, benzoylation, and phenylation of the stannylpyrazoles were examined

The reaction of 3-bromopyridine with phenylacetonitrile in the presence of NaH in THF gave a simple substitution product, α-phenyl-3-pyridineacetonitrile, whereas the reaction of 5-bromopyrimidine with phenylacetonitrile under similar conditions gave a ring-transformation product, 2-amino-5-bromo-3-phenylpyridine. 3-bromoquinoline and 4-bromoisoquinoline underwent the former type reaction, while 3-bromo- and 3-chloroisoquinolines were converted into 2-amino-3-phenyl-1-naphthalencarbonitrile according to the latter type reaction

Inverse electron-demand Diels-Alder reaction of 3,6-disubstituted 1,2,4,5-tetrazines with tributylstannylacetylenes containing a substituent gave 4-(tributylstannyl)pyridazines. Particularly, dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate gave 4-(tributylstannyl)pyridazines in good yields. Substitution reaction of 3,6-diphenyl-4-(tributylstannyl)pyridazine was also described

4 H -1,3-Dioxin was firstly arylated by using Heck reaction, and the reaction in the presence of ( R )-BINAP gave enantiomerically enriched 4-phenyldioxin which was converted into optically active 1-phenyl-1,3-propanediol.

1,3-Dioxep-5-ene was arylated by using Heck reaction, and the arylated 1,3-dioxep-4-ene derivatives were easily converted into 4-arylbutyrolactones, intermediates for the synthesis of natural products and biological active compounds

Methyl 2-(nitrogen-heteroaryl)propanoates were synthesized by the palladium-catalyzed reaction of heteroaryl halides with (E)-1-methoxy-1-trimethylsiloxypropene

Palladium-catalyzed reaction of aryl and heteroaryl iodides with ethoxy(trialkylstannyl)acetylenes gave the ethoxyethynylarenes and -heteroarenes, which were easily transformed by hydration reaction into ethyl areneacetates and heteroareneacetates.

The palladium-catalyzed cross-coupling reaction of bromobenzenes or bromoheteroarenes such as pyridine, thiophene, indole with ( Z )-1-ethoxy-2-tributylstannylethene gives good yields of the corresponding ( Z )-1-ethoxy-2-(aryl and heteroaryl)ethenes. This method is effective for introducing an ethoxyethenyl group into an aromatic and heteroaromatic ring and is proved to have versatile utility for the construction of benzo[ b ]furan, indole, isocoumarin rings from 2-bromophenol, 2-bromoaniline, and 2-bromobenzoate derivatives.

3-Substituted 5-(tributylstannyl)isoxazoles were newly synthesized by the 1,3-dipolar cyctoadditton of nitrile oxides to tributylethynylstannane. The iodination and the palladium-catalyzed benzoylation of 5-(tributylstannyl)-3-methylisoxazolegave 5-iodo-3-methylisoxazole and 3-methyl-5-isoxazolyl phenyl ketone in satisfactory yields, respectively. The palladium-catalyzed cross-coupling reaction of the stannylisoxazole with 2-bromonitrobenzene followed by the catalytic hydrogenation over Raney nickel resulted in the formation of 2-methyll-4(1H)-quinolinone in 57% overall yield.

Diglycolic acid (DGA) oxidizing activity was found in crude extracts of Rhodococcus sp. no. 432 grown in DGA. Glycolic acid (GA) oxidase was purified approximately 80 times by treatment with streptomycin sulfate, precipitation with (NH4)2SO4, chromatographies with DEAE-cellulose, DEAE-Toyopearl and Butyl-Toyopearl, and gel filtration on Toyopearl HW-55. The purified GA oxidase was almost homogeneous on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The purity was calculated to be more than 95%. The molecular weight of the enzyme, which appeared to consist of three identical units, was 158,000. Each subunit of GA oxidase included one molecule of FAD as a cofactor. The isoelectric point of the enzyme was around 5.3. GA oxidase was stable below 30°C and at the pH range of 6.0–8.5. The optimum pH and temperature were around 7.5 and 40°C, respectively. Oxygen, cytochrome c, ferricyanide and 2,6-dichlorophenol indophenol (DCIP) acted as an electron acceptor. The activity of GA oxidase was strongly inhibited by potassium cyanide, quinine, quinacrine, monoiodoacetate, 1,4-benzoquinone and some heavy metal ions. GA oxidase also had activity in DGA, GA, glyoxylic acid (GOA), methoxy acetate, ethoxy acetate and l -malate. Alcohols and other organic acids were not oxidized by the enzyme. The apparent Km values for DGA, GA and GOA were about 26.7, 0.5 and 4.4 mM, respectively. The reaction products from DGA were supposed to be GOA and GA by the enzymatic assays. The reaction mechanism of GA oxidase in oxidation of DGA was supposed to be as follows: HOOCH2COCH2COOH+H2O+acceptor→HOOCCHO+HOOCCH2OH+ reduced acceptor.

The palladium(0)-catalyzed condensation of aryl halides with the sodium salts of phenylsulfonylacetonitrile and diethyl cyanomethylphonate in dimethoxyethane gave the corresponding α-phenylsulfonylareneacetonitriles and diethyl arylcyanomethylphosphonates in good yields.The α-phenylsulfonylareneacetonitriles were easily desulfonylated with zinc to give the areneacetonitriles, and the arylcyanomethylphonates were converted to the alkylideneareneacetonitriles by means of the Horner-Emmons reaction.

Palladium-catalyzed cyclization of β-(2-halophenyl)amino substituted α,β-unsaturated ketones and esters, prepared from 2-haloanilines by three different methods, gave 2,3-disubstituted indoles.

1, 3-Dipolar cycloaddition reaction of trimethylstannylacetylene with nitrile oxides yielded 3-substituted 5-(trimethylstannyl)isoxazoles. On the other hand, the same reaction of (trimethylstannyl)phenylacetylene, -1-hexyne, and -(trimethylsilyl)acetylene gave 3, 5-disubstituted 4-(trimethylstannyl)isoxazoles almost regioselectively. The regioselectivity of the cycloaddition reaction is interpreted by application of the frontier-electron theory.

The palladium-catalyzed cross-coupling reaction of aryl iodides with 3,3,3-triethoxy-1-propyne gave 1-aryl-3,3,3-triethoxy-1-propynes which were converted to the corresponding ethyl arylpropiolates. The arylpropiolates were also synthesized from the cross-coupling reactions of aryl iodides with 2-ethoxycarbonyl-1-ethynylzinc chloride or ethyl (tributylstannyl)propiolate, but the reactions were not generally applicable

The Cu(I)-catalyzed boration of an α,β-enone using a diboron is described. Combination of a Cu(I) salt and tributylphosphine is an effective catalyst system, though the individual use of Cu(I) and tributylphosphine is not active for the reaction.

The syntheses and reactions of pyrimidines N-oxides are reviewed. Pyrimidines having alkyl, aryl, and alkoxyl groups are convertible to their mono-N-oxides by N-oxidation with an organic peroxy acid. The position of the N-oxide group can be elucidated by physical methods. Pyrimidine N-oxides are highly reactive to various nucleophilic reagents owing to their π-deficient character. The reactivity of a methyl group enhanced by introducing an N-oxide group and the characteristic ring-cleavage of N-oxides are also described

Rigidin, a marine alkaloid, was synthesized by the combination of acylation via lithiation and arylation by palladium-catalyzed reaction starting from 2,4-dimethoxypyrrolo[2,3- d ]pyrimidine.

Methyl α-methoxyarylacetates 3 have been synthesized by the palladium-catalysed reaction of iodobenzenes 1 with α-methoxyketene methyl silyl acetals 2. The diastereoselective and enantioselective synthesis of the arylacetates has also been examined.

Indolylzinc derivatives were prepared by the oxidative addition of active zinc to iodoindoles, which coupled with aromatic halides in the presence of palladium catalyst to give arylated indoles.

The oxidative addition of active zinc to bromo- and iodopyridines gave pyridinylzinc halides which were coupled with aryl halide or benzoyl chloride in the presence of a palladium catalyst.

Indolylzinc halides are prepared by two methods: transmetallation of indolyllithiums with zinc chloride and oxidative addition of active zinc to iodoindoles. The palladium-catalysed reaction of the indolylzinc halides provides a practical method for synthesizing arylindoles.

1,3-Dipolar cycloaddition reaction of trimethylstannylacetylene with phenyl azide gave a regioselective product, 1-phenyl-4-trimethylstannyl-1,2,3-triazole. On the other hand, the reaction of trimethylstannyl-1-hexyne, -phenylacetylene, and -trimethylsilylacetylene with the azide yielded a mixture of the corresponding 4- and 5-trimethylstannyl-1-phenyl-1,2,3-triazoles. Detrimethylstannylation, iodination, benzoylation, and palladium-catalyzed phenylation of 4-trimethylstannyl- and 4,5-bis(trimethylstannyl)-1-phenyl-1,2,3-triazoles were also described

Methyl 2-(nitrogen-heteroaryl)propanoates were synthesized by the palladium-catalyzed reaction of heteroaryl halides with (E)-1-methoxy-1-trimethylsiloxypropene

1,3-Dioxep-5-ene was arylated by using Heck reaction, and the arylated 1,3-dioxep-4-ene derivatives were easily converted into 4-arylbutyrolactones, intermediates for the synthesis of natural products and biological active compounds

2-Arylindoles were synthesized by the palladium-catalyzed reaction of aryl halides with 2-indolylzinc derivatives which were derived from the lithio derivatives