美丽红豆杉二萜的研究——Ⅱ.一个新的紫杉烷二萜的结构

在前文[1]中,我们报道了从美丽红豆杉茎皮中分离得到的三个非紫杉烷二萜型的新的二萜化合物1、2和3.本文报道从美丽红豆杉茎皮中分到的两个紫杉烷二萜化合物:经高分辩~1H NMR 和 COSY 测定其结构为红豆杉素 J(taxinine J,4)和2-去乙酰氧基-红豆杉素J(2-deacetoxy-taxinine J,5)4是已知的,5是新化合物.初步药理结果表明:4和5对肝癌细胞具不同程度的抑制作用.     

软珊瑚Sarcophyton crassocaule中西松烷大环二萜

软珊瑚Sarcophyton种属多含有细胞毒性的西松烷型(cembrane)的大环二萜[1～5],我们对采自中国南海西沙群岛的软珊瑚Sarcophyton crassocaule化学成分进行了生物活性跟踪研究,从对癌细胞P-388具有明显抑制活性的CHCl3提取物中分离得到了一个已知结构和两个新西松烷型(cembrane)的大环二萜.我们首次报道了其中一个结构新颖的过氧西松烷型(cembrane)的大环二萜Sarcocrassolide A(3)的分离和结构鉴定,化合物的结构经1H NMR,13C NMR,HMQC,1H-1H COSY,NOESY,FABMS和X-ray晶体衍射,确证其结构和相对构型.     

芫花花蕾中的两个新二萜

瑞香烷型二萜类化合物具有良好的抗肿瘤生理活性.为了进一步研究该类抗肿瘤活性成分,对富含瑞香烷型二萜的芫花花蕾进行化学成分研究,从中分离得到一个巴豆烷型二萜1和两个瑞香烷型二萜原酸酯2和3.应用多种波谱学方法（1H NMR,13C NMR,HSQC,HMBC,NOESY,ESI-MS,HR-ESI-MS等）,确定了3个化...     

海绵Spongia sp.中一个新的D环为吡啶环的降海绵烷型二萜（英文）

在对一种Spongia属海绵的化学成分研究中,分离得到一个新的降海绵烷型二萜dinorspongiapyridine(1)和四个已知化合物2～5.通过核磁共振波谱、单晶X-ray衍射以及对比文献的方法,确定了这些化合物的结构及其绝对构型.化合物1是首次发现的D环为吡啶环的3,4-裂环-3,19-双降海绵烷型二萜类化合物,并对其细胞毒活性进行了测试.此外,对化合物1的生物合成途径也进行了探讨.     

长叶暗罗中克罗烷型二萜及其抗炎作用

对长叶暗罗茎的化学成分进行研究,分离得到4个新的克罗烷型二萜类化合物,通过NMR、HR-ESI-MS等多种现代波谱技术鉴定为:2-氧代-14,15,16-降三碳克罗烷-3-烯-13-酸(1)、2-氧代-14,15,16-降三碳克罗烷-3-烯-13-甲酯(2)、2-氧代-14,15,16-降三碳克罗烷-3,11E-二烯-13-酸(3)、2-氧代-16-羟基-克罗烷-3,13Z-二烯-15-酸(4).其中,化合物1～3为降三碳克罗烷型二萜,所有化合物均表现出一定的抗炎活性, IC50值范围为9.24～18.82μmol/L.     

新的19-降海绵烷二萜的分离及结构确定

从海洋海绵Spongiazimoccaaubspeclesirregularia中分离到一种新的19-降海绵烷二萜(ZimoclactoneA,1)和胆甾-5,7-二烯-3β-醇,化合物1的化学结构和立体化学通过波谱方法和X射线单晶衍射分析确定,化合物1对P388肿瘤细胞具有中等程度的细胞毒活性.     

荞麦地鼠尾草根中的二萜类成分

对民间丹参代用品荞麦地丹参(Salvia kiaometiensis Lévl.)乙醇提取物进行化学成分研究,通过现代多种色谱技术和波谱技术,从中分离并鉴定16个二萜类化合物,分别是6,8,11,13-abietatetraen-12-ol dimer(1),kiaometin(2),miltirone(3),tanshinone IIA(4),crypotanshione(5),tanshindiol C(6),ferruginol(7),2-isopropyl-8-methylphenanthrene-3,4-dione(8),tanshinone I(9),trijuganone B(10),dihydrotanshinone I(11),grandifolias C(12),przewalskin(13),tanshinlactone(14),6,7,8,9-tetrahydro-1,6,6-trimethylfuro[3,2-c]naphtha[2,1-e]oxepine-10,12-dione(15),almilalbanone(16).其中,化合物1为新的松香烷型二萜的二聚体,2为新的降松香烷型二萜化合物,其B环7,8位开环后又通过醚桥连接起来.所有化合物均为首次从该种植物中得到.     

毛叶酯和毛叶醇的化学结构

从河南毛叶香茶菜的干叶中分得两种新的ent-16-kaurene型二萜化合物-毛叶酯和毛叶醇,由光谱分析和化学反应确定其结构为1和2.同时还分得已知化合物Lasiokaurino(3)     

稀有植物四川金粟兰化学成分的进一步研究

对稀有植物四川金粟兰(Chloranthus sessilifolius)全草甲醇提取物开展进一步化学成分研究,从中分离得到2个二萜类、1个苯丙素类、1个黄酮类和1个木脂素类化合物.利用多种波谱和光谱技术(如红外、紫外、1D/2D NMR、ECD、HR-ESIMS)结合相关文献中的理化数据确定了它们的结构分别为:(3R,5S,6S,9S,10S,13S)-3,6,13-三羟基-对映松香烷-8(14)-烯-7-酮(1)、3α,15-二羟基-13α-甲氧基-对映松香烷-8(14)-烯-7-酮(2)、p-香豆酰-β-苯乙胺(3)、柚皮素三甲基醚(4)和(3R,4R,3'R,4'R)-6,6'-二甲氧基-3,4,3',4'-四氢-2H,2H'-[3,3']-双色原烯-4,4'-二醇(5).其中,化合物1为新的对映松香烷型二萜,而3~5则均为首次从金粟兰属植物中分离得到的化合物.     

肉芝软珊瑚属中二聚西松烷型二萜化合物的化学和生物活性研究进展

二聚西松烷型二萜(biscembranoid)是一类骨架新颖、结构复杂、罕见的海洋天然产物,主要存在于肉芝软珊瑚属珊瑚生物中.这类化合物多具有显著的生物活性,尤其表现为抗炎、抗肿瘤等.对近年来报道的肉芝软珊瑚属中的二聚西松烷型二萜化合物的化学及生物活性进行综述,并对其药用前景作出展望.     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.