中国南海海绵Seletta tenuis lindgren中24-亚甲基-27-甲基胆甾醇的结构鉴定

本研究中国南海海绵生物活性成分的过程中,从南海海绵中分离出24-亚甲基-27-甲基胆甾醇,通过IR,^1HNMR,^13CNMR,^1H-^13CCOSY,MS和MS-MS等波谱分析,确证了其化学结构,并详细报道了波谱数据.     

24-亚甲基-27-甲基胆甾醇的结构鉴定

从中国南海海绵 seletta tenuis lindgren 中分离出具有心血管活性的24-亚甲基-27-甲基胆甾醇(1)。通过各种波谱分析,推导其化学结构,并确定了~(13)C NMR 数据的归属。     

南海海绵Axinyssa aplysinoides的化学成分研究(二)

从中国南海采集的海绵Axinyssaaplysinoides中分离得到一白色结晶 ,通过UV ,IR ,MS ,NMR等波谱方法和光谱技术 ,确定了它的结构为Δ2 2 (2 3 ) (E) - 2 4 ,2 6 ,2 6-三甲基 - 2 5(30 ) -亚甲基胆甾醇     

南海黄蜂海绵中系列长链甲基酮成分分析

从中国南海海绵Spheciospongia Vagabunda乙酸乙酯萃取部分中分离出一组混合物,应用^13HNMR,^13CNMR,H-HCOSY和GC／MS等光谱分析技术对它们的结构进行了分析,主要为一些长链甲基酮化合物。共鉴定出二十四碳烯-2-酮异构体、二十四碳二烯-2-酮和二十四碳烯-2-酮等14种化合物,其中4种化合物的双键位置有待于进一步确定。     

南海海绵Biemna fortis化学成份的研究(一)

从中国南海海绵Biemnafortis的乙酸乙酯可溶部分中分离得到化合物 2 4 -甲基胆甾 - 7 2 2E -二烯 - 3β,5α -二羟基 - 6-酮 ,其结构由IR、MS、1 HNMR等分析手段得以确定     

南海海绵Iotrochota ridley化学成分的研究(-)

从中国南海海绵Iotrochotaridley中分离到一种长链甘油醚，其结构经IR，MS，1HNMR，13CNMR，1H－1HCOSY确定为3-十八烷氧基-1，2-丙二醇（鲨肝醇）（Ⅰ）。本文是首次报道该种属海绵的化学成分。     

南海海绵Axinyssa aplysinoides的化学成份研究(一)

从南海海绵Axinyssaaplysinoides中分离得到一甘油醚类化合物C2 7H54 O3。利用IR ,MS,NMR等分析手段确定了它的结构为 1 -( 1 7Z -二十四碳烯基 ) -甘油醚。     

南海海绵Biemna fortis中一种环二氧甾醇

从中国南海海绵Biemnafortis的乙酸乙酯可溶部分分离出一个已知的有机化合物 ,经IR ,EIMS ,1HNMR等光谱分析确定其化学结构式为 :5α ,8α -环二氧 -2 4 ξ -甲基胆甾 -6,2 2 -二烯 -3 β -醇。     

中国南海海绵Phakellia sp化学成份的分离和结构鉴定

海绵是最原始的多细胞动物,我国南海有几千种。国外从海绵中发现了多种新颖萜类、甾体和一些含氮、硫、卤素和带特异官能团的化合物。其中有些化合物具有学术上的重要意义,有些具有很强的生理活性,有些则已发展     

南海海绵Rhabdastrella属中新胆甾醇Rhabdasterol

人们已从海绵生物中发现了许多结构独特的有机化合物,如萜类、甾醇、苷类、生物碱、多肽和聚醚等,其中许多具有广谱抗菌、抗病毒、抗心血管病和抗肿瘤等生理活性．本文报道从我国南海海绵Ｒｈａｂｄａｓｔｒｅｌａｓｐ．中分离出一个具有新型侧链的胆甾醇：２５（２９）...     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).