利用自由基反应合成（S）-（＋）-娃儿藤碱及其类似物

通过自由基反应,成功的合成了（S）-（＋）-娃儿藤碱（1）及其类似物．以2,3,6,7．四甲氧基菲甲酸为原料通过两或三步分别制得（-）-N-（2,3,6,7,四甲氧基-9-菲苄基）．2．溴甲基四氢吡咯（7）和（-）-N-（2,3,6,7-四甲氧基-9-菲甲酰基）-2-溴甲基四氢吡咯（9）．在催化量的偶氮二异丁腈参与下,溴化物（7）与三正丁基氢化锡反应没有得到预期的产物（S）-（＋）-娃儿藤碱,却以较高的收率得到N-（2,3,6,7-四甲氧基-9-菲苄基）哌啶（2）.通过分析机理,改用溴化物（9）为底物在同样的条件下分别以33．6％和65％的收率制得（S）-（＋）-9-娃儿藤酮（10）和（-）-N-（2,3,6,7-四甲氧基-9-菲甲酰基）-2-甲基四氢吡咯（11）．通过实验发现,化合物（10）和（11）的收率与偶氮二异丁腈的加入量密切相关．我们认为偶氮二异丁腈在该反应中充当着双重角色,并提出了可能机理．化合物（10）和（11）经四氢锂铝还原顺利得到（S）-（＋）-娃儿藤碱（1）和其结构类似物（＋）-N-（2,3,6,7-四甲氧基-9-菲苄基）-2-甲基四氢吡咯．     

保幼激素类似物11-甲氧基-3,7,11-三甲基-2,4-十二碳二烯酸异丙酯的简便全合成

从价廉的丙酮出发,首先经羟醛缩合、脱水、氧化、酯化、溴代反应合成了4-溴-3-甲基-2-丁烯酸异丙酯,继而与亚磷酸三乙酯反应得到了Wittig-Homer试剂,随后与香茅醛发生Wittig-Horner反应,最后在阳离子树脂催化作用下与甲醇醚化,成功地全合成了具有保幼激素活性的昆虫生长调节剂11-甲氧基-3,7,11-三甲基-2,4-十二碳二烯酸异丙酯.所得标题化合物的四种异构体中,具有较高生物活性的(2E,4E)-异构体的含量达66%.各步所合成化合物的结构经1H NMR,IR,MS分析确证.     

大黄素衍生物的合成及细胞毒性研究

以天然大黄素为母体, 经化学修饰得到一系列新的含氮衍生物6～14. 通过¹H NMR, IR, MS和元素分析确定了结构. 选择口腔底癌(KB)和乳腺癌(MFC-7)两种人癌细胞株, 采用标准MTT法测定了这类大黄素衍生物的细胞毒性. 研究表明大多数衍生物都有较强的抗癌活性, 其中位置异构体7a和7b的混合物表现出最强的活性, 与母体大黄素相比较, 活性分别提高了174倍(KB)和133倍(MFC-7).     

Synthesis of SMND-309, a derivate of salvianolic acid B

(E)-2-(6-((E)-2-carboxyvinyl)-2,3-dihydroxyphenyl)-3-(3,4-dihydroxyphenyl) acrylic acid, designated SMND-309, was synthesized starting from 2-hydroxy-3-methoxybenzaldehyde in 12 steps and with an overall yield of 44%. The synthetic key features were the conversion of aryl aldehyde into aryl acetic acid for one-carbon extended, the Perkin condensation, and the Heck coupling for construction of α,β-unsaturated ester.     

Total Synthesis and Biological Evaluation of Grassypeptolide A

Herein, we describe in full our investigations into the synthesis of grassypeptolide A ( 1 ) in 17 linear steps with an overall yield of 11.3 %. In particular, this work features the late‐stage introduction of sensitive bis(thiazoline) heterocycles and 31‐membered macrocyclization conducted at the sterically congested secondary amide site in superb conversion (72 % yield). Biological evaluation indicated that grassypeptolide A significantly inhibited cancer cell proliferation in a dose‐dependent manner. It induced cancer cell apoptosis, which was associated with increased cleavage of poly(ADP‐ribose) polymerase (PARP) and decreased expression of bcl‐2 and bcl‐xL. Furthermore, grassypeptolide A also caused cell cycle redistribution by increasing cells in the G1 phase and decreasing cells in the S and G2 phases. In addition, cell cycle arrest was correlated with downregulation of cyclin D and upregulation of p27 and p21.     

Total Synthesis of Limonin

Limonoids are highly oxygenated C13α‐triterpenes and common secondary metabolites. Several hundred congeners have been isolated to date. The first total synthesis of (±)‐limonin, the flagship congener of the limonoids, is now reported and features 1) a tandem radical cyclization generating the BCD ring system with the C13α configuration that is essential to the limonoids and a Robinson annulation to construct the limonoid androstane framework, 2) a singlet‐oxygen cycloaddition and a Baeyer–Villiger oxidation to synthesize the highly oxidized D ring, and 3) a Suárez reaction to construct the unique AA′ ring system.     

Isolation and Asymmetric Total Synthesis of Perforanoid A

A novel limonoid, perforanoid A, was isolated, and an asymmetric total synthesis was achieved in 10 steps. The key steps are chiral tertiary aminonaphthol mediated enantioselective alkenylation of an aldehyde to an allylic alcohol, Pd‐catalyzed coupling of the allylic alcohol with vinyl ether to form the γ‐lactone ring, and cyclopentenone ring formation through a Rh‐catalyzed Pauson–Khand reaction. Preliminary studies show that perforanoid A is cytotoxic towards HEL, K562, and CB3 tumor cell lines.     

Asymmetric Total Synthesis of (+)‐Ryanodol and (+)‐Ryanodine

(+)‐Ryanodine ( 1 ) is the ester derivative of 1H‐pyrrole‐2‐carboxylic acid and the complex terpenoid (+)‐ryanodol ( 2 ), which possesses eleven contiguous stereogenic centers on the ABCDE‐ring system. Compound 1 is known to be a potent modulator of intracellular calcium release channels, whereas the activity of 2 is significantly weaker. To chemically construct 1 , the multiple oxygen functional groups must be installed on the fused pentacycle in stereoselective fashions and the extremely hindered C3‐hydroxy group must be acylated in a site‐selective manner. First, the total synthesis of 2 was accomplished by introducing the five stereocenters from the previously prepared enantiopure ABDE‐ring 7 . Stereoselective construction of the C3‐secondary, C2‐ and C6‐tertiary alcohols was achieved by three nucleophilic reactions. The C9‐ and C10‐trisubstituted carbon centers were regio‐ and stereoselectively introduced by hydroboration/oxidation of the six‐membered C‐ring, which was formed by the ring‐closing metathesis reaction. Direct esterification of the C3‐alcohol with pyrrole‐2‐carboxylic acid proved unsuccessful; therefore, we developed a new, two‐step protocol for attachment of the pyrrole moiety. The C3‐hydroxy group was first converted into the less sterically cumbersome glycine ester, which was then transformed into the pyrrole ring through condensation with 1,3‐bis(dimethylamino)allylium tetrafluoroborate. This procedure resulted in the first total synthesis of 1 .     

Collective Total Synthesis of 4-Azafluorenone Alkaloids

4-Azafluorenones are typically obtained by acid-mediated cyclization of 2-arylnicotinates. However, this approach fails to give 5-oxygenated 4-azafluorenones due to lactonization of 2-(2-alkoxy)phenylnicotinate intermediates. Herein, we report two modifications of established approaches to 4-azafluorenone synthesis that, either in combination or by themselves, enable the flexible preparation of 4-azafluorenones with diverse oxygenation patterns in the benzenoid ring. Undesired lactonization was circumvented via tert-butyl hydroperoxide (TBHP)-mediated radical cyclization of 2-aryl-3-(hydroxymethyl)pyridines. In the absence of suitable protecting groups for phenolic intermediates, bromide substituents were regioselectively introduced as latent hydroxy groups and later converted under palladium catalysis. We present the first total syntheses of five 4-azafluorenone alkaloids muniranine, darienine, 5,8-dimethoxy-7-hydroxyonychine, 5,6,7,8-tetramethoxyonychine, and 6,8-dihydroxy-7-methoxyonychine in addition to new total syntheses of six 4-azafluorenone alkaloids and one related pyridocoumarin alkaloid.     

1-苯基-3-甲基-6-N,N-二正丁基胺-2(1H)-喹喔啉-2-酮的全合成

报道了2(1H)-喹喔啉类衍生物——1-苯基-3-甲基-6-N,N-二正丁基胺-2(1H)-喹喔啉-2-酮的全合成.该化合物及其中间体1-苯基-3-甲基-6-胺基-2(1H)-喹喔啉-2-酮和1-苯基-3-甲基-6-硝基-2(1H)-喹喔啉-2-酮均为新化合物,文中给出了它们的重要的分析数据,简要讨论了溶剂在关环反应以及N-烷基化反应中的重要影响,偶然发现以水作溶剂时关环主产物为1-苯基-3-甲基-5-硝基-苯并咪唑.这类化合物可应用于药物,如用作N-甲基-D-天冬氨酸(NMDA)受体及α-氨基羟甲基异噁唑丙酸(AMMPA)受体拮抗剂、杀菌剂等;还可用作植物生长抑制剂、荧光探针以及作为新型功能染料中间体等诸多领域.     

Synthesis of light alkenes on manganese promoted iron and iron-cobalt Fischer-Tropsch catalysts

The Perkin reaction is accompanied by competitive transformations of the intermediate carbanions. These transformations are found to be inhibited by the reacting aldehydes. The limiting stage of the Perkin reaction is NACC attack (nucleophilic attack at carbonyl carbon) of amines on the anhydride.     

Total Synthesis,Stereochemical Revision,and Biological Assessment of Iriomoteolide-2a

Iriomoteolide-2a is a marine macrolide metabolite isolated from a cultured broth of the benthic dinoflagellate Amphidinium sp. HYA024 strain. This naturally occurring substance was reported to show remarkable cytotoxic activity against human cancer cell lines HeLa and DG-75 and in vivo antitumor activity against murine leukemia P388 cell line. Herein, the total synthesis, stereochemical revision, and biological assessment of iriomoteolide-2a are reported in detail. Total synthesis of the proposed structure 1 of iriomoteolide-2a featured a late-stage convergent assembly of three components by a Suzuki–Miyaura coupling, an esterification, and a ring-closing metathesis. However, the NMR data of synthetic 1 were not identical to those of the natural product. Careful analysis of the NMR data of the authentic material and synthesis/NMR analysis of appropriately designed model compounds led to consideration of four possible stereoisomers 2 – 5 as candidates for the correct structure. Accordingly, total syntheses of 2 – 5 were achieved by taking advantage of the convergent strategy, and comparison of the NMR spectra of synthetic 2 – 5 with those of the natural product led to the conclusion that 5 shows the correct relative configuration of iriomoteolide-2a. The absolute configuration of this natural product was finally established through chiral HPLC analysis of synthetic 5 /ent- 5 with the authentic sample. The antiproliferative activity of the synthetic compounds was assessed against HeLa and A549 cells to show that, in contrast to expectation, synthetic 5 and ent- 5 were only marginally active in these cell lines. This work clearly underscores the vital role of total synthesis in the establishment of the structure and biological activity of natural products.