Bong Young Chung

Synthesis and biological evaluations of pyrazolo[3,4-d]pyrimidines as cyclin-dependent kinase 2 inhibitors.

A series of 1,4,6-trisubstituted pyrazolo[3,4-d]pyrimidines 15-19, 30-38 capable of selectively inhibiting CDK2 activity were synthesized by derivatization at C-4, C-6 and N-1 with various amines and lower alkyl groups. For above synthetic compounds, biological evaluation was carried out and structure-activity relationship was examined. In our series, 4-anilino compounds exhibited better CDK2 inhibitory activity and antitumor activity compared to 4-benzyl compounds. The compounds 33a,b having a 3-fluoroaniline group at C-4 showed comparable or superior CDK2 inhibitory activity to those of olomoucine and roscovitine as reference compounds. In general, the unsubstituted compounds (30a,b, 33a,b, 36a,b) at N-1 possessed higher potency than the substituted compounds (32a,b, 34a,b) for the CDK2 inhibitory activity. As for EGFR inhibitory activity, most compounds didnot have a significant activity. The compounds 32a,b exhibited potent cell growth inhibitory activity against human cancer cell lines, but their CDK2 inhibitory activities were slightly poorer than olomoucine.

Indium mediated pinacol coupling reaction of aromatic aldehydes in aqueous media

Abstract The carbon-carbon bond formation reaction of aromatic carbonyl compounds was performed with indium in neutral aqueous media using sonication affording the corresponding diols in moderate to good yields.

Solution-phase combinatorial synthesis of isoxazolines and isoxazoles using [2+3] cycloaddition reaction of nitrile oxides

Abstract An efficient way to construct a library of isoxazoles and isoxazolines was developed by solution-phase 1,3-dipolar cycloaddition reaction of nitrile oxides with olefins and alkynes followed by precipitation of the products as HCl salts.

Asymmetric synthesis of both enantiomers of novel tetracyclic heterocycle, furo[3′,2′:2,3]pyrrolo[2,1-a]isoquinoline derivative via a diastereoselective N-acyliminium ion cyclization

Abstract An efficient synthesis of both enantiomers of tetracyclic isoquinoline derivative (−)- 2 and (+)- 2 was accomplished starting from L-malic acid and L-tartaric acid, respectively. The key step is the stereoselective introduction of quaternary carbon-center in ring juncture using a diastereoselective N -acyliminium ion cyclization of chiral enamides ( 1, 3 ).

A new direct allylation of the aromatic compounds with allylic chlorides catalyzed by indium metal

Abstract A new method of the direct allylation reaction for the aromatic compounds with allylic chlorides using a catalytic amount of indium in the presence of CaCO 3 4 A molecular sieves was developed.

[18F]-labeled isoindol-1-one and isoindol-1,3-dione derivatives as potential PET imaging agents for detection of β-amyloid fibrils

In this study a novel series of isoindol-1-one and isoindol-1,3-dione derivatives for beta-amyloid-specific binding agents is described. Twelve compounds were synthesized and evaluated via a competitive binding assay with [(125)I]TZDM against beta-amyloid 1-42 (Abeta42) aggregates. Two new [(18)F]-labeled isoindole derivatives were synthesized and evaluated as potential beta-amyloid imaging probes based on the in vivo pharmacokinetic profiles. The preliminary results suggest that these [(18)F]18b and [(18)F]18c are promising positron emission tomography (PET) imaging probes for studying accumulation of Abeta fibrils in the brains of Alzheimers disease (AD) patients.

Synthesis of new pyrrolidine C-nucleosides via Staudinger-aza-Wittig cyclization of γ-azido ketone

Abstract Novel N -acetyl C -aza-2-deoxy- d -ribonucleosides were synthesized from 2-deoxy- d -ribose via a consecutive procedure of the addition of ortho-lithiated pyrimidine salt, Staudinger-aza-Wittig ring cyclization, and reduction of cyclic imine.

Synthesis of (+)-muscarine from (S)-(−)-5-hydroxymethyl-2(5H)-furanone

Abstract (+)-Muscarine has been synthesized from ( S )-(−)-5-hydroxy-2(5 H )-furanone via rather a long pathway to provide easy access to a wide variety of its analogues.

Novel phosphinobioxazines as chiral ligands in palladium-catalyzed enantioselective allylic substitution

Abstract Novel C 2 -symmetric chiral (4 S ,4′ S )-bisphosphinobioxazine 2a , a six-membered analog of (4 S ,4 S ′)-bisphosphinobioxazoline (Phos-Biox, 1 ), and monophosphinobioxazine 2b have been synthesized and used as chiral ligands for Pd-catalyzed asymmetric allylic substitutions of rac- 1,3-diphenyl-2-propenyl acetate with dimethyl malonate. C 2 -Symmetric bisphosphinobioxazine 2a exhibited moderate enantioselectivities (63–84% ee) whereas excellent enantioselectivities (94–95% ee) were observed with monophosphinobioxazine 2b .

Synthesis and evaluation of stilbenylbenzoxazole and stilbenylbenzothiazole derivatives for detecting β-amyloid fibrils

This paper describes a novel series of stilbenylbenzoxazole (SBO) and stilbenylbenzothiazole (SBT) derivatives for beta-amyloid specific binding probes. These 24 compounds were synthesized and evaluated by competitive binding assay against beta-amyloid 1-42 (Abeta42) aggregates using [(125)I]TZDM. All the derivatives displayed higher binding affinities with K(i) value in the subnanomolar range (0.10-0.74 nM) than Pittsburgh Compound-B (PIB) (0.77 nM). Among these derivatives, SBT-2, 5-fluoroethoxy-2-{4-[2-(4-methylaminophenyl)vinyl]phenyl}benzothiazole, showed lowest K(i) value (0.10 nM). In conclusion, the preliminary results suggest that these compounds are implying a possibility as a probe for detection of Abeta fibrils in Alzheimers disease (AD) patients.