Concise total synthesis of phidianidine A and B

The shortest total synthesis of cytotoxic indole alkaloids phidianidine A and B is described. Rapid assembly of the 1,2,4-oxadiazole core from a novel N-hydroxyguanidine and the corresponding indole-3-acetic acid chloride led to formal syntheses of phidianidine A and B in only three steps from known compounds. Deprotection under standard conditions provided the trifluoroacetate salts of phidianidine A and B in quantitative yield.     

Concise total synthesis of calothrixins A and B

The concise total synthesis of calothrixins A and B has been accomplished by utilizing the one-pot formation of hexatriene as a key intermediate via the palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate. In another key transformation, the indolo[3,2-j]phenanthridine core was prepared in high yield via Cu(I)-mediated 6π-electrocyclization.     

Concise, asymmetric total synthesis of spirotryprostatin A

The structurally intriguing cell-cycle inhibitor spirotryprostatin A has been synthesized utilizing an azomethine ylide dipolar cycloaddition reaction as the key step. This pentacyclic alkaloid contains a prenylated tryptophan-derived oxindole moiety that has been created in a regiocontrolled and stereocontrolled manner in a single step.     

1,4—二苯基—2—苯氧基—1,4,2—二氮磷杂环戊—5—酮的合成及其除草活性研究

利用１，３－二苯基脲与亚磷酸三苯酯和取代苯甲醛进行的类Ｍａｎｎｉｃｈ反应合成了１，４－二苯基－２－苯氧基－１，４，２－二氮磷杂环戊－５－酮（２），所有新化合物的结构均经元素分析、ＮＭＲ、ＭＳ证实。对目标化合物进行的除草活性测试结果表明，２对阔叶杂草具有较好的选择性除草活性。     

1－对甲苯磺酰基－2－氧代－2－苯氧基－3－芳基－1，4，2－二氮磷杂环戊－5－硫酮的合成及其除草活性

通过１－苯基－３－对甲苯磺酰基硫脲（１）与亚磷酸三苯酯和取代苯甲醛在甲苯中进行的类Ｍａｎｎｉｃｈ反应合成１－对甲苯磺酰基－２－氧代－２－苯氧基－３－芳基－１，４，２－二氮磷杂环戊－５－硫酮（２）．本文对合成过程中所涉及到的副反应进行了初步探讨，初步的生物活性测定结果表明，化合物２具有一定的除草活性。     

Versicolactones A and B: total synthesis and structure revision

To further determine absolute configurations of versicolactones A and B, total synthesis of versicolactones A and B and their six stereoisomers were reported in this Letter. The ¹H and ¹³C NMR spectra of the synthetic erythro-stereoisomers matched perfectly with those of the natural products. Combined with the comparison of the specific rotations, the absolute configuration of versicolactones A and B were revised as (4Z,6R,7S)- and (4E,6R,7S)- from the corresponding (4Z,6R,7R)- and (4E,6R,7R)-6,7-dihydroxyocta-2,4-dien-4-lactone, respectively.     

Stereoselective total synthesis of sporiolide B and attempted synthesis of sporiolide A

A simple and efficient stereoselective total synthesis of sporiolide B and attempted synthesis of sporiolide A, from epichlorohydrin, using asymmetric synthetic approach is reported. The key reactions involved are Sharpless epoxidation, Jacobsen reaction, syn-allylation, Yamaguchi esterification, and Grubbs ring-closing metatheses reaction to result in the macrocyclic ring system.     

First total synthesis of rhuscholide A,glabralide B and denudalide

The first total synthesis of rhuscholide A, a benzofuran lactone possessing anti-HIV-1 activity, had been accomplished in 14 linear steps with 10.6% overall yield. In this synthesis, base-mediated phenol ortho-alkylation and piperidine promoted aldol condensation were exploited as key steps. The synthesis was flexible and allowed for the convenient preparation of two analogous natural products glabralide B and denudalide.     

Synthesis and Herbicidal Activity of Novel Sulfonylureas Containing Thiadiazol Moiety

Thirteen novel sulfonylureas containing thiadiazole moiety were synthesized in a two-step reaction. Their structures were determined using IR, ^1H NMR, HRFTMS, and elemental analysis. Herbicidal activities of these compounds were determined in the green house bio-assay. The results show that four compounds among them exhibit some activity toward four tested herbs.     

苯环2-位不同酯基取代的磺酰脲类化合物的合成及其除草活性

以正在开发的磺酰脲类超高效除草剂NK94827[N'-(4'-甲基嘧啶-2'-基)-2-甲氧羰基苯磺酰脲]的基本结构为基础,设计合成了18个苯环2位不同酯基取代的的新型磺酰脲类化合物,产物结构均经¹HNMR及元素分析确证.经油菜平皿法和盆栽试验测试除草活性,所合成的部分磺酰脲化合物的除草活性高.     

Stereoselective synthesis and moulting activity of integristerone A and analogues

Integristerone A, a rare ecdysteroid of plant origin, has been synthesized from 20-hydroxyecdysone with 2-deoxy-1,2-didehydro-20-hydroxyecdysone as the key intermediate, followed by stereoselective asymmetric dihydroxylation. The analogues 1,2-di-epi-integristerone A and 1,2-di-epi-5α-integristerone A have also been synthesized. Integristerone A exhibited approximately 9-fold lower moulting activity than the parent 20-hydroxyecdysone in the Musca domestica bioassay, indicating that the presence of a 1β-hydroxyl group resulted in a decrease in activity. As expected, the 1,2-di-epi-5α-analogue was inactive in this assay.     

Concise, asymmetric, stereocontrolled total synthesis of stephacidins A, B and notoamide B

Concise asymmetric total syntheses of the fungal metabolites (-)-stephacidin A, (+)-stephacidin B, and (+)-notoamide B are described. Key features of these total syntheses include (1) a facile synthesis of (R)-allyl proline methyl ester, (2) a revised route toward the pyranoindole ring system, (3) a novel cross-metathesis strategy for the introduction of important functional groups, and (4) an SN2' cyclization to form the [2.2.2] bridged bicyclic ring system. Furthermore, our synthesis has taken advantage of microwave heating to shorten reaction times as well as increase yields for the preparation of vital intermediates.     

First total synthesis and reassignment of absolute configuration of diosniponol A and B

Enantioselective first total synthesis of diosniponol A and B has been achieved starting from commercially available vanillin. Wittig reaction, Keck allylation, and Prins cyclization reactions are the key steps involved in the target synthesis.     

1-芳基-2-苯基-3-甲基-3-异丙基-2-氧代-1,4,2-二氮磷杂环戊-5-酮的合成及除草活性

利用取代苯基脲与苯基二氯化膦和3-甲基-2-丁酮进行的类Mannich反应合成了15种新的1,4,2-二氮磷杂环戊-5-酮类化合物(2a_2o), 其结构经     

A short synthetic route to the core structures of otteliones A and B

Conjugate addition of the cuprate derived from 2-lithio-2,3-butadiene to 1-cylopentenecarbaldehyde, reaction with vinylmagnesium bromide, ring closing metathesis, and oxidation gives the cis-ring fused core of the anticancer agent ottelione A. Epimerization of the initial conjugate addition product and application of the same reactions as used for the ottelione A core, give the trans-ring fused core of ottelione B.     

Concise synthesis of quinazoline alkaloids, luotonins A and B, and rutaecarpine

The total synthesis of luotonin A was achieved in excellent yield by using a Pd-assisted biaryl coupling reaction of N-(bromoquinolinyl)methylquinazolinone with Cy₃P and KOAc. The successive treatment of luotonin A with NBS and aq. AgNO₃ gave luotonin B in good yield. Although the Pd-assisted coupling reaction of N-(2-bromoindolyl)ethylquinazolinone with Cy₃P and KOAc yielded rutaecarpine in poor yield, N-acetate under the same reaction conditions yielded the desired rutaecarpine directly in excellent yield.     

First total synthesis of the marine steroid alkaloid plakinamine B

The first total synthesis of the marine steroid alkaloid plakinamine B (1) was accomplished in seven steps starting from known aldehyde 3. Key steps in this synthesis are the attachment of a vinylpyridine side chain by an aldol reaction, a chemoselective reduction of a pyridinium salt to a vinyl tetrahydropyridine, and the introduction of the 3α-methylamino group under Mitsunobu conditions. Plakinamine B and some of its precursors with amino or pyridinium side chains show significant antimicrobial activities.     

新磺酰脲类化合物的合成及生物活性

以正在开发的新磷磺酰脲除草剂N-[2′-(4′-甲基)嘧啶基]-2-硝基苯磺酰脲的研究为基础,设计合成了19个脲桥经修饰的磺酰脲类化合物以及3个新型嘧啶中间体,产物结构经¹HNMR谱及元素分析确证.盆栽试验和离休ALS酶研究结果表明,所合成的化合物均表现出一定的除草活性,部分化合物的除草活性较好.     

First total synthesis of two new heterocyclic compounds:Bretschneiderazines A and B

Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A（2） and B（3）,isolated from an extract of the stems of Bretschneidera sinensis,is reported.We employed the cyclization reaction of benzamide by directed lithiation and sequential treatment with sulfur and phosgene as key steps.All new compounds have been fully characterized by means of IR,¹H NMR,¹³C NMR,and HRMS.