Moon-Kook Jeon

Controlling side-chain density of electron donating polymers for improving their packing structure and photovoltaic performance

A simple and efficient approach of controlling the side-chain density in the electron donating polymers has been demonstrated to tune their 3-D packing structure and HOMO level, which increases the hole mobility and V(oc) values, thus improving the solar cell performance.

Synthesis and anticancer activity of new 1-[(5 or 6-substituted 2-alkoxyquinoxalin-3-yl)aminocarbonyl]-4-(hetero)arylpiperazine derivatives

A series of novel quinoxalinyl-piperazine compounds, 1-[(5 or 6-substituted alkoxyquinoxalinyl)aminocarbonyl]-4-(hetero)arylpiperazine derivatives were synthesized and evaluated as an anticancer agent. From screening of quinoxalinyl-piperazine compound library, we identified that many compounds inhibited proliferation of various human cancer cells at nanomolar concentrations. Among them, one of the fluoro quinoxalinyl-piperazine derivatives showed its IC(50) values ranging from 11 to 21nΜ in the growth inhibition of cancer cells. This compound also displayed a more potent effect than paclitaxel against paclitaxel resistant HCT-15 colorectal carcinoma cells. The potency of this novel compound was further confirmed with the synergistic cytotoxic effect with several known cancer drugs such as paclitaxel, doxorubicin, cisplatin, gemcitabine or 5-fluorouracil in cancer cells. This strong cell killing effect was derived from the induction of apoptosis. Mechanistic studies have shown that this quinoxalinyl-piperazine compound is a G2/M-specific cell cycle inhibitor and inhibits anti-apoptotic Bcl-2 protein with p21 induction. Thus the results suggest that our compound has potential use in the growth inhibition of drug resistant cancer cells and the combination therapy with other clinically approved anticancer agents as well.

Synthesis of new5-alkylidene-4-chloro-5H-1,2,3-dithiazoles and their stereochemistry

Abstract A variety of5-alkylidene-4-chloro-5H-1,2,3-dithiazoles (9–25) have been prepared from4-chloro-5H-1,2,3-dithiazolium chloride, active methylene compounds, and pyridine. The reactions with ethyl nitroacetate ((Z) > (E)), ethyl 3-nitrobenzoylacetate ((E) > (Z)), ethyl 2-fluorobenzoylacetate ((E) > (Z)), and tetronic acid ((Z) > (E)) gave a mixture of(E)-and(Z)-isomers, whereas those of benzoylnitromethane (Z),5,6-dihydro-4-hydroxy-6-methyl-2H-pyran-2-one (E), 4-hydroxy-6-methyl-2-pyrone (E), 4-hydroxycoumarin (E), 6-chloro-4-hydroxycoumarin (E), and 6-bromo-4-hydroxycoumarin (E) afforded only single stereoisomers. The reactions with4-hydroxy-1-methyl-2(1H)-quinolone, 2-hydroxy-1,4-naphthoquinone and homophthalic anhydride gave only single stereoisomers whose stereochemistry is uncertain. It appears that geometrically more rigid cyclic 1,3-dicarbonyl compounds give better yields of dithiazol-5-ylidenes than the corresponding acyclic compounds. Download : Download full-size image

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.

A facile synthesis of 5-[(arylamino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones

Treatment of 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione with primary arylamines in CH2Cl2 at rt gave 5-[(arylamino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones in excellent yields. The latter compounds were utilized for the preparation of 2-cyano-4-quinolinones.

SYNTHESIS OF NEW 2H-1,4-THIAZINES AND THEIR DERIVATIVES UTILIZING N,N-(DI-N-ALKYL)-N'-ARYLTHIOCARBAMOYLAMIDINES

The reactions of N,N-(di-n-alkyl)-N′-arylthiocarbamoylamidines (1) with 2-bromo-1-phenylethanone in the presence of K2CO3 in THF at reflux gave 3-(di-n-alkylamino)-2-arylimino-5-phenyl-2H-1,4-thiazines (7) in 32 to 62% yields. Treatment of compounds 1 with bromoacetyl bromide in the presence of pyridine in CH2Cl2 at 0 °C afforded 5-(di-n-alkylamino)-6-arylimino-2H-1,4-thiazin-3-ones (12) in 41 to 84 % yields, whereas the same reactions of 1 with 2-bromopropionyl bromide under the same conditions gave 4-(di-n-alkylamino)-5-arylimino-2-(1-bromoethylidene)-2H-thiazolines (17) as minor compounds in addition to thiazin-3-ones 16, analogous to compounds 12. The reactions of 1 with ethyl bromoacetate in CH2Cl2 at room temperature, however, gave [(arylimino)(S-ethoxycarbonylmethyl)]methyl-N,N-(di-n-propyl)amidine hydrobromides (19) in 71 to 88 % yields. Compounds 7, 12, 16, 17, and 19 are all new and the mechanisms of their formations are proposed.

Synthesis of 3-(alkylamino and anilino)-4-benzyloxycarbonyl-1H-pyrrole-2,5-diones via 5-[(alkylamino and anilino)(cyano)]-2,2-dimethyl-1,3-dioxane-4,6-diones

Treatment of [(alkylamino and anilino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones with benzyl alcohol for 20 min at reflux gave 3-(alkylamino and anilino)-4-benzyloxycarbonylmaleimides.

Novel synthesis of 1-aryl-3-chloro-3-phenylazetidin-2-one-4-spiro-5′-4′- chloro-5′H-1′,2′,3′-dithiazoles and bis(2-oxo-azetidin-4-yl) trisulfides

Treatment of 5-arylimino-4-chloro-5H-1,2,3-dithiazoles with in situ generated (chloro)phenylketene in CH2Cl2 at rt gave azetidin-2-one-4-spiro-5′-(1′,2′,3′-dithiazoles) as major products, which reacted with primary and secondary alkylamines in CH2Cl2 at rt to afford bis(2-oxo-azetidin-4-yl) trisulfides in good to excellent yields.

Reactions of 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione with primary and secondary alkylamines

The reactions of 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione with primary alkylamines (2 equiv.) in CH2Cl2 at rt gave 5-[(alkylamino)(cyano)methylidene]-2,2-dimethyl-1,3-dioxane-4,6-diones (2) in excellent yields. Similarly, the reactions with ethylenediamine, trans-1,2-diaminocyclohexane, 2-aminobenzylamine, and 2-aminoethanol under the same conditions afforded 5-(imidazolidin-2-ylidene)- (3a), 5-(octahydro-2H-benzimidazol-2-ylidene)- (3b), 5-[3,4-dihydroquinazolin-2(1H)-ylidene]- (3c), and 5-(1,3-oxazolidin-2-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (3d) in moderate to excellent yields. Interestingly, the reactions with secondary acyclic dialkylamines under the same conditions yielded 5-(4-dialkylamino-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (7) (0–60%), 6-carbamoyl-5-oxo-5H-furo[2,3-d][1,2,3]-dithiazoles (8) (0–28%), sulfur, and bis(dialkylamino) sulfides (R2N–Sx–NR2), whereas the reactions with cyclic amines, i.e., pyrrolidine and piperidine, gave the corresponding methylidene-Meldrums acid derivatives 9, analogous to 2, as major products. Mechanisms are proposed for the formation of these products.