• Bulletin of the Korean Chemical Society
• /
• v.34 no.10
• /
• pp.2871-2876
• /
• 2013

We present an efficient and new preparative method for the symmetric ${\beta}$-diketimines assisted by microwave. A series of N,N'-symmetrically alkyl substituted ${\beta}$-diketimines have been synthesized from the reaction of O-acylation with dimethylsulfate. Higher reproducibility and yield, lower cost and much improved green nature originated from no solvent condition and higher energy efficiency due to faster reaction time are major merits of this new method. In addition to these merits, almost every kind of ${\beta}$-diketimines including alkyl-substituted ${\beta}$-diketimines little reported yet has been successfully prepared. Much wider applications of these compounds in various fields are expected.

• YAKHAK HOEJI
• /
• v.18 no.2
• /
• pp.161-164
• /
• 1974

m-Hydroxyaniline was reported to be converted to m-methoxyaniline with dimethylsulfate. However, while repeating the experiment with the same reaction condition, it was learned that the reaction product was not m-methoxyaniline but m-methoxy dimethylaniline. It was confirmed with nmr and ir spectrum and the comparison of bp and mp of the derivatives. Elemental analyses of the derivatives were also consistant with the fact N-dimethylation along with O-methylation occurred.

• Applied Chemistry for Engineering
• /
• v.21 no.1
• /
• pp.93-97
• /
• 2010

Polyaniline doped with ionic liquid (1,3-dimethylimidazolium methylsulfate, I-DMS) soluble in polar solvents (NMP, DMSO, DMF, m-cresol etc.) were synthesized by nucleophilic addition. Solubilities of PAN/I-DMS powder in polar solvents were observed in the range of 3~6 wt%/vol., respectively. The electrical conductivities of PAN/I-DMS films appeared in the range of $10^{-2}{\sim}7S/cm$. Polyaniline doped with I-DMS (PAN/I-DMS) showed improved thermal stability and conductivity compared to that of HCl doped polyaniline (PAN/HCl) and dimethylsulfate (DMS) doped polyaniline (PAN/DMS) upon heat treatment at $160^{\circ}C$. These improved conductivity and solubility in organic polar solvents was explained with the interactions between the polar sulfonate group and polar solvents.

• Korean Journal of Pharmacognosy
• /
• v.36 no.2 s.141
• /
• pp.116-120
• /
• 2005

Paeonol (2-hydroxy-5-methoxyacetophenone) obtained by silica gel column chromatography of the essential oil extracted from Paeonia moutan (Paeoniaceae) was methylated by dimethylsulfate to yield methylpaeonol (2,5-di-O-methylacetophenone). Both compounds inhibited nitric oxide (NO) foundation in lipopolysaccharide-induced macrophage RAW 264.7 cells in nitrite assay. In the western blotting assay, it was shown that both compounds also decreased inducible nitric oxide synthase (iNOS)-and cyclooxygenase-2(COX-2) formation. Methylpaeonol produced more potently inhibited NO-, iNOS and COX-2 formation in the assays than paeonol. These results suggest that paeonol is in part responsible for anti-inflammatory activity of Paeonia moutan, and that synthesis of paeonol derivatives may produce a promising candidate for andtiifnalmmatory agent.

• Archives of Pharmacal Research
• /
• v.21 no.4
• /
• pp.440-444
• /
• 1998

A series of 6-(N-arylamino)-7-methylthio-5,8-quinolinedione derivatives 4a-4l was newly synthesized for the evaluation of antifungal activity. 6-(N-Arylamino)-7-methylthio-5,8-quinolinediones were prepared by regioselective nucleophilic substitution of 6,7-dichloro-5,8-quinolinediones with arylamines in the presence of $Ce^{3+}$, and $Na_2$S/dimethylsulfate. The MIC values of 4a-4l were determined for antifungal susceptibility in vitro against Candida species by agar streak method. The derivatives 4a-4l had generally potent antifungal activities against all human pathogenic fungi. Especially they had the most potent activity against C. krusei at 12.5-0.8 $\mu\textrm{g}$/ml. Compounds 4d, 4g, 4h, 4j and 4k had more potent antifungal activities than fluconazole. Compounds 4g and 4h completely inhibited the fungal growth at 0.8-6.3 $\mu\textrm{g}$/ml against all Candida species, while fluconazole inhibited the growth at 25 $\mu\textrm{g}$/ml. The compounds such as 4g and 4h containing an N-(4-bromo-2-methylphenyl)- or N-(4-bromo-3methylphenyl)amino substituent exhibited the most potent antifungal activities.

• Journal of the Korean Chemical Society
• /
• v.39 no.9
• /
• pp.734-740
• /
• 1995

The primary and secondary structures of Xanthomonas palargonii 5S rRNA were determined. The higher order structure of the 5S rRNA was also analysed using several ribonucleases and chemical probes, such as ethylnitrourea, Pb2+, dimethylsulfate and diethyl pyrocarbonate. Ethylnitrourea was used for probing the phosphate groups involved in the tertiary interactions in the 5S rRNA. Nucleotides G72, A73, G75, A78, G98, G100 and A101 in unstable helical region d, nucleotides C36, C37, A39, and C41 in loop c, nucleotides A29 and G33 in stem C became resistant to ethylnitrourea modification in the presence of Mg2+. On the basis of findings from chemical and enzymatic studies, and also Pb2+-induced cleavages, it was concluded that region b-C and unstable helical region d may act as hinges in the folding of 5S rRNA.

• BMB Reports
• /
• v.28 no.6
• /
• pp.509-514
• /
• 1995

A putative secondary structure of the mRNA for the human hepatitis B virus (HBV) X gene is proposed based on not only chemical and enzymatic determination of its single- and double-stranded regions but also selection by the computer program MFOLD for energy minimum conformation under the constraints that the experimentally determined nucleotides were forced or prohibited to base pair. An RNA of 536 nucleotides including the 461-nucleotide HBV X mRNA sequence was synthesized in vitro by the phage T7 RNA polymerase transcription. The thermally renatured transcripts were subjected to chemical modifications with dimethylsulfate and kethoxal and enzymatic hydrolysis with single strand-specific RNase T1 and double strand-specific RNase V1, separately. The sites of modification and cleavage were detected by reverse transcriptase extension of 4 different primers. Many nucleotides could be assigned with high confidence, twenty in double-stranded and thirty-seven in Single-stranded regions. These nucleotides were forced and prohibited, respectively, to base pair in running the recursive RNA folding program MFOLD. The results suggest that 6 different regions (5 within X mRNA) of 14~23 nucleotides are Single-stranded. This putative structure provides a good working model and suggests potential target sites for antisense and ribozyme inhibitors and hybridization probes for the HBV X mRNA.