Young-Dae Gong

Solid-phase synthesis of thiazolo[4,5-b]pyridine derivatives using Friedländer reaction.

Traceless solid-phase synthesis of 2,5,6,7-tetrasubstituted thiazolo[4,5-b]pyridine derivatives is described. Thorpe-Ziegler type cyclization of solid supported cyanocarbonimidodithioate with alpha-halo ketones afforded thiazole resin, which were converted to the desired thiazolopyridine resin by the Friedländer protocol under microwave irradiation conditions. After oxidation of sulfides to sulfones, nucleophilic desulfonative substitution with amines gave the target thiazolo[4,5-b]pyridine derivatives in good overall yields.

Traceless Solid-Phase Synthesis of 2,4,6-Trisubstituted Thiazolo[4,5-d]pyrimidine-5,7-dione Derivatives

An expedient, traceless, solid-phase synthesis of 2,4,6-trisubstituted thiazolo[4,5-d]pyrimidine-5,7-dione derivatives has been developed. The solid-phase synthetic route utilizes urea formation by a microwave irradiation promoted reaction of a thiazole amino ester resin with an isocyanate. The resulting urea resin is converted to a thiazolopyrimidinedione resin, containing two diversity elements at N-4 and N-6, by using a one-pot cyclization/N-alkylation process. After oxidation to form a sulfone, nucleophilic C-2 substitution with amines, the third diversity element, gives the target 2,4,6-trisubstituted thiazolo[4,5-d]pyrimide-5,7-dione derivatives. This highly efficient solid-phase synthetic sequence enables the incorporation of three points of diversity into the preparation of the thiazolo[4,5-d]pyrimidine-5,7-dione ring system.

Solid-Phase Synthesis of 1,3,6-Trisubstituted-1H-thiazolo[4,5-c][1,2]thiazin-4(3H)one-2,2-dioxide Derivatives using Traceless Linker

A new solid-phase route for preparation of 1,3,6-trisubstituted-1H-thiazolo[4,5-c][1,2]thiazin-4(3H)one-2,2-dioxide derivatives is described. Our synthetic route is begun with a thiazole resin and relies on the sulfonamide formation, Mitsunobu-type N-alkylation, cyclization, and nucleophilic substitution methodology cleavage on a solid support. The strategy permits the incorporation of three points of diversity into the thiazolo[4,5-c][1,2]thiazine ring system in good overall yields.

Novel solid-phase parallel synthesis of N-substituted-2-aminobenzo [d]thiazole derivatives via cyclization reactions of 2-iodophenyl thiourea intermediate resin.

A novel solid-phase methodology has been developed for the synthesis of N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo[d]thiazole resins 5 by cyclization reaction of 2-iodophenyl thiourea resin 3. The resin-bound 2-iodophenyl thiourea 3 is produced by addition of 2-iodophenyl isothiocyanate 2 to the amine-terminated linker amide resin 1. These core skeleton 2-aminobenzo[d]thiazole resins 5 undergo functionalization reactions with various electrophiles, such as alkyl halides, acid chlorides, and sulfonyl chlorides to generate N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole resins 6, 7, and 8, respectively. Finally, N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole derivatives 9, 10, and 11 are then generated in good yields and purities by cleavage of the respective resins 6, 7, and 8 using trifluoroacetic acid (TFA) in dichloromethane (DCM).

Identification of 3-hydroxy-2-(3-hydroxyphenyl)-4H-1-benzopyran-4-ones as isoform-selective PKC-ζ inhibitors and potential therapeutics for psychostimulant abuse

From a screen of small molecule libraries to identify potential therapeutics for psychostimulant abuse, 3-hydroxy-2-(3-hydroxyphenyl)-4H-1-benzopyran-4-ones were shown to be isoform-selective PKC-zeta inhibitors.

Application of Thio-Ugi Adducts for the Preparation of Benzo[b]thiophene and S-Heterocycle Library via Copper Catalyzed Intramolecular C-S Bond Formation.

Fused heterocycles, such as benzo[b]thiophene, thiochroman, benzo[b][1,4]thiazine, and 1,4-benzothiazepine were generated from thio-Ugi adducts containing a thioamide group through copper-catalyzed intramolecular C-S bond formation under microwave irradiation.

Discovery of (2-Fluoro-Benzyl)-(2-Methyl-2-Phenethyl-2H-Chromen-6-yl)-Amine (KRH-102140) as an Orally Active 5-Lipoxygenase Inhibitor with Activity in Murine Inflammation Models

Objective and Design: We investigated anti-inflammatory properties of a novel 5-lipoxygenase (5-LO) inhibitor, KRH-102140, in vitro and in vivo. 5-LO enzyme activity was assayed using insect cell lysates overexpressing rat 5-LO. The leukotriene B4 (LTB4) level was assayed in rat basophilic leukemia (RBL-1) cell line. ICR (Institute of Cancer Research) mice were used for in vivo assays. Mouse ear edema was induced by topical application of arachidonic acid. An air pouch was induced by subcutaneous injection of sterile air into mice, followed by zymosan treatment. Sprague-Dawley rats were used for pharmacokinetic studies. Results: KRH-102140 inhibited 5-LO activity with an IC50 value of 160 ± 23 nmol/l in parallel with LTB4 inhibition in RBL-1 cells. Oral administration of KRH-102140 (10–100 mg/kg) reduced ear edema, myeloperoxidase activity and LTB4 production in murine inflammation models. Oral bioavailability as determined in rats was 66%. Conclusions: Our results show that KRH-102140, a new 5-LO inhibitor, exhibits potent anti-inflammatory activities in vitro as well as in vivo.

A Highly Efficient Diversification of 2-Amino/Amido-1,3,4-oxadiazole and 1,3,4-Thiadiazole Derivatives via Reagent-Based Cyclization of Thiosemicarbazide Intermediate on Solid-Phase.

A 2-amino/amido-1,3,4-oxadiazole and 1,3,4-thiadiazole library has been constructed on solid-phase organic synthesis. The key step on this solid-phase synthesis involves the preparation of polymer-bound 2-amino-1,3,4-oxadiazole and 1,3,4-thiadiazole core skeleton resin by cyclization of thiosemicarbazide with EDC·HCl and p-TsCl, respectively. The resulting core skeleton undergoes functionalization reaction with various electrophiles such as alkyl halides, and acid chlorides to generate N-alkylamino and N-acylamino-1,3,4-oxadiazole, and 1,3,4-thiadiazole resin, respectively. Finally, the 2-amino and 2-amido-1,3,4-oxadiazole and 1,3,4-thiadiazole library was then generated in good yields and high purities by cleavage of the respective resin under trifluoroacetic acid(TFA) in dichloromethane(DCM). The constructed library shows reasonable, oral bioavailability drug properties as determine by using the Lipinskis Rule and similar parameters.

Identification of Metabolites of N-(5-Benzoyl-2-(4-(2-Methoxyphenyl)piperazin-1-yl)thiazol-4-yl)pivalamide Including CYP3A4-Mediated C-Demethylation in Human Liver Microsomes with High-Resolution/High-Accuracy Tandem Mass

KRO-105714 [N-(5-benzoyl-2-(4-(2-methoxyphenyl)piperazin-1-yl)thiazol-4-yl)pivalamide] is a 2,4,5-trisubstituted 1,3-thiazole derivative that exerts anti–atopic dermatitis activity via robust suppression of the sphingosylphosphorylcholine receptor. This study used high-resolution/high-accuracy tandem mass spectroscopy (HRMS) and recombinant cDNA–expressed cytochrome P450 (P450) isoforms to identify the metabolic pathway and metabolites of KRO-105714 in human liver microsomes (HLMs) as therapeutic agents for inflammation. The incubation of KRO-105714 with pooled HLMs in the presence of NADPH generated four metabolites (M1–M4). The metabolites were identified using HRMS and confirmed using synthetic standards for M2 and M4. M1 and M2 were identified as monohydroxylated metabolites, and M3 and M4 were identified as O-demethyl KRO-105714 and C-demethyl KRO-105714, respectively. In the inhibition study with selective CYP3A4 inhibitors and incubation in recombinant cDNA–expressed P450 enzymes, all the metabolites of KRO-105714 were formed by CYP3A4 in HLMs. The CYP3A4-mediated formation of M4 from M2 was confirmed via incubation of M2 in HLMs. These results showed that the unusual C-demethylated metabolite M4 was generated from monohydroxyl metabolite M2 via a CYP3A4-mediated enzymatic reaction in HLMs.

Solid-phase synthesis of novel 7,8-functionalized pyrazolo[1,5-a][1,3,5]-2-oxo-4-thioxotriazine derivatives via cyclization reactions of dithiocarboxy resin bound pyrazoles.

A general method is described for the solid-phase synthesis of novel 7,8-functionalized pyrazolo[1,5-a][1,3,5]-2-oxo-4-thioxotriazine derivatives. The sequence developed for this purpose is based on cyclization reactions of resin-bound 3,4-functionalized-5-amino-1-dithiocarboxypyrazoles 4 and 5, promoted by reaction with various isocyanates. The resin-bound pyrazoles produced by cyclization reactions of cyanocarboimidates 8 or 3-ethoxyacrylonitriles 9 with Merrifield resin linked hydrazine dithiocarbazate 3, serve as key intermediates for subsequent bicyclic heterocycle diversification. Reactions of the resin-bound 5-amino-1-dithiocarboxy pyrazoles 4 and 5 with various aryl isocyanates produce the novel 7,8-functionalized pyrazolo[1,5-a][1,3,5]-2-oxo-4-thioxotriazine derivatives 6 and 7 in good yields and high purities.