排序方式: 共有8条查询结果,搜索用时 0 毫秒
1
1.
2.
Poolsak SahakitpichanSomsak Ruchirawat 《Tetrahedron letters》2003,44(28):5239-5241
The Amaryllidaceae alkaloid buflavine 1 has been synthesized in three steps by Suzuki-Miyaura cross coupling, reduction and the cascade reactions of Pictet-Spengler type and Eschweiler-Clarke N-methylation. 相似文献
3.
Thongchai Jeerasuda Paramote Poolsak 《AEUE-International Journal of Electronics and Communications》2008,62(9):666-673
In this paper, a new analysis technique of an ordinary second-order oscillator which is based on multi-time concept is proposed. This mathematical analysis results in a new closed-form solution of a system complete response. It is found that amplitude of the natural response is not constant but varied with the forced response of the system. For a constant forcing function proposed, the new analysis is identical to the conventional analysis. In the case of time-varying forcing function, however, it is different from the conventional approach. Based on such analysis, it implies that the amplitude of a second-order oscillator can easily be controlled by forced response of the system. Hence, the obtained result based on the proposed analysis technique provides a proper mathematical solution for the system, especially in a time-varying forcing function. Moreover, the mathematical analysis for the wide-band characteristic of a second-order oscillator is also described. The experimental results demonstrate the responses of the oscillator which agree well between the theoretical and simulation results. 相似文献
4.
Poolsak Sahakitpichan 《Tetrahedron》2004,60(19):4169-4172
Lennoxamine and related isoindolobenzazepines were prepared in high yield by intramolecular condensation of aldehyde isoindolones under basic conditions followed by catalytic hydrogenation of the resulting dehydroisoindolobenzazepines. 相似文献
5.
6.
Total synthesis of natural and unnatural lamellarins with saturated and unsaturated D-rings 总被引:1,自引:0,他引:1
Ploypradith P Petchmanee T Sahakitpichan P Litvinas ND Ruchirawat S 《The Journal of organic chemistry》2006,71(25):9440-9448
Twenty-eight natural and unnatural lamellarins with either a saturated or an unsaturated D-ring were synthesized according to our developed synthetic route. The key step involved the Michael addition/ring closure (Mi-RC) of the benzyldihydroisoquinoline and alpha-nitrocinnamate derivatives, which provided the 2-carboethoxypyrrole intermediates in moderate to good yields (up to 78% yield). Subsequent hydrogenolysis/lactonization furnished lamellarins with a saturated D-ring in excellent yields (up to 93% yield). DDQ oxidation of the saturated lamellarin acetates led directly to the corresponding unsaturated analogues in 54-95% yield. In addition, only two steps in our developed strategy require column chromatography. 相似文献
7.
Sahakitpichan P Disadee W Ruchirawat S Kanchanapoom T 《Chemical & pharmaceutical bulletin》2011,59(9):1160-1162
A new 3-hydroxydihydrobenzofuran glucoside, gnaphaliol 9-O-β-D-glucopyranoside (2), was isolated from the aerial parts of Gnaphalium polycaulon together with 1-{(2R*,3S*-3-(β-D-glucopyranosyloxy)-2,3-dihydro-2-[1-(hydroxyl methyl)vinyl]-1-benzofuran-5-yl}-ethanone or gnaphaliol 3-O-β-D-glucopyranoside (1), (Z)-3-hexenyl O-β-D-glucopyranoside (3) and adenosine (4). The absolute configurations at C-2 and C-3 positions of compound 1 were determined to be 2R and 3R. The structures of these compounds were elucidated on the basis of their physical and spectroscopic data. 相似文献
8.
Wannaporn DisadeeChulabhorn Mahidol Poolsak SahakitpichanSomkit Sitthimonchai Somsak Ruchirawat Tripetch Kanchanapoom 《Tetrahedron》2011,67(23):4221-4226
Six new flavonol 3-O-robinobiosides and 3-O-(2″-O-α-l-rhamnopyranosyl)-robinobiosides, sesuviosides A-F, were isolated from the aerial portion of Sesuvium portulacastrum together with ecdysterone, adenosine, 2′-O-methyladenosine, and l-tryptophan. The structure elucidations were based on analyses of chemical and spectroscopic data including 1D and 2D-NMR. Sesuviosides A-F and their aglycones exhibited radical scavenging activity using DPPH and ORAC assays. 相似文献
1