New cytotoxic constituents from the Red Sea soft coral Nephthea sp.

Nephthea are soft coral species rich in sesquiterpenoids and steroids. An organic extract of Nephthea sp. resulted in the isolation of a new steroid (1), as well as several previously reported metabolites (2–9). Structures were elucidated by employing NMR and HR-EI-MS analyses. The total extract, fractions and purified compounds exhibited differential cytotoxicity against the breast cancer MCF-7 cell line.     

β石墨炔衍生物结构稳定性及电子结构的密度泛函理论研究

石墨炔衍生物比石墨烯具有更多样化的原子结构,因而具有潜在的更丰富的电子结构.通过第一性原理密度泛函理论研究方法系统研究了β石墨炔衍生物的结构稳定性、原子构型和电子结构.本文计算的β石墨炔衍生物系列体系由六边形碳环(各边原子数N=1—10)通过顶点相连而成.对结构与能量的计算分析表明:当N为偶数时,β石墨炔拥有单、三键交替的C—C键结构,其能量比N为奇数时,拥有连续C=C双键的石墨炔衍生物更稳定.计算的能带结构和态密度显示:根据碳环各边原子个数N的奇偶性不同,β石墨炔可呈现金属性(N为奇数时)或半导体特性(N为偶数时).该奇偶依赖的原子构型和电学性质是由Jahn-Teller畸变效应导致,与碳环各边原子碳链的实际长度无关.计算发现部分半导体β石墨炔(N=2,6,10)呈现狄拉克锥能带特征,其带隙约10 meV,且具有0.255×10~6—0.414×10~6m/s的高电子速度,约为石墨烯电子速度的30%—50%.本密度泛函理论研究表明,将sp杂化碳原子引入石墨烯六边形碳环的边上,可通过控制六边形各边原子个数的奇偶性调制其金属和半导体电子特性或狄拉克锥的形成,为免掺杂和缺陷调控纳米碳材料的电学性质和设计碳基纳米电子器件提供了理论依据.     

C−C Coupling of Benzyl Fluorides Catalyzed by an Electrophilic Phosphonium Cation

The activation and cleavage of benzyl fluorides by the electrophilic organofluorophosphonium catalyst, [(C₆F₅)₃PF][B(C₆F₅)₄], is reported and used for the preparation of 1,1‐diarylalkanes (37 examples) and substituted aryl homoallylic alkenes (14 examples). This procedure involves mild conditions, avoids harmful waste, and is compatible with a range of substituted arenes and allylic silanes.     

PhI(OAc)2/I2-Mediated Decarboxylative C4-Amination of Coumarin-3-Carboxylic Acids via Csp2−H Dehydrogenative C−N Cross-Coupling under Ambient Conditions

An efficient and straightforward protocol for accessing a new series of functionalized 4-aminocoumarins from PIDA/I₂-mediated decarboxylative C₄-amination of coumarin-3-carboxylic acids via direct C_sp2−H dehydrogenative C−N cross-coupling with secondary amines under ambient conditions has been accomplished. The notable advantages of this protocol are the tolerance of diverse functional groups, mild reaction conditions at ambient temperature, moderate to good yields, short reaction times (in minutes), high regioselectivity, gram-scale applicability, and eco-friendliness. This is the first report of decarboxylative C_sp2−H cross-dehydrogenative C−N coupling of coumarin-3-carboxylic acids for synthesizing 4-aminocoumarins.     

Complete assignments of (1)H and (13)C NMR spectral data of nine surfactin isomers

A new surfactin isomer (1) was isolated from a mangrove bacteria strain 'Bacillus sp'. Its structure was identified, and full assignments of (1)H and (13)C NMR spectral data were achieved for the first time by a combination of mass spectrometry and 1D and 2D NMR experiments including DEPT, (1)H-(1)H COSY, HSQC, HMBC, TOCSY, ROESY, and HSQC-TOCSY. The NMR spectral data of eight known analogs (2-9) are also reported.     

Lobozoanthamine, a new zoanthamine-type alkaloid from the Indonesian soft coral Lobophytum sp.

A new member of the family of zoanthamine-type alkaloids, lobozoanthamine (1), has been isolated from the Indonesian soft coral Lobophytum sp. This represents the first report of a zoanthamine-type alkaloid from a marine invertebrate different from zoanthids. The densely functionalized heptacyclic stereostructure of lobozoanthamine (1) has been established through the interpretation of 2D NMR data and application of the modified Mosher method.     

Synthesis of 6-oxacyclopropa[a]indene derivatives starting from Baylis–Hillman adducts via Pd-mediated C(sp)–H activation

We prepared novel 1-phenyl-1,6a-dihydro-6-oxacyclopropa[a]indene-1a-carboxylic acid derivatives starting from the Baylis–Hillman adducts via the palladium-mediated domino carbopalladation involving activation of C(sp³)–H bond.     

Cytotoxic Activity of Capnellene‐8β, 10α‐Diol Derivatives from a Taiwanese Soft Coral Capnella sp.

The sesquiterpene capnellene‐8β, 10α‐diol ( 1 ) was isolated from non‐polar extract of the soft coral Capnella sp. Ten acylation products of capnellene‐8β, 10α‐diol were prepared: 10α‐hydroxy‐8β‐O‐benzoylcapnellene ( 2 ), 10α‐hydroxy‐8β‐O‐p‐toluoylcapnellene ( 3 ), 10α‐hydroxy‐8β‐O‐4‐chlorobenzoyl‐capnellene ( 4 ), 10α‐hydroxy‐8β‐O‐2‐furoylcapnellene ( 5 ), 10α‐hydroxy‐8β‐O‐2‐thiophenoylcapnellene ( 6 ), 10α‐hydroxy‐8β‐O‐4‐fluorobenzoylcapnellene ( 7 ), 10α‐hydroxy‐8β‐O‐4‐propylbenzoylcapnellene ( 8 ), 10α‐hydroxy‐8β‐O‐cinnamoylcapnellene ( 9 ), 10α‐hydroxy‐8β‐O‐4‐nitrobenzoylcapnellene ( 10 ), and 10α‐hydroxy‐8β‐O‐4‐anisoylcapnellene ( 11 ). The structures of capnellene‐8β, 10α‐diol as well as its derivatives were established through standard spectroscopic analysis. The in vitro cytotoxic activities of the eleven compounds were evaluated against Hela, KB, Daoy, and WiDr human tumor cell lines.     

Three New Sesquiterpenoids from Xylaria sp. NCY2

Three new sesquiterpenoids, xylarenones A ( 1 ) and B ( 2 ), and xylarenic acid ( 3 ), were obtained from the endophytic fungal strain Xylaria sp. NCY2, which was isolated from Torreya jackii Chun . Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments, and by HR‐Q‐TOF mass spectrometry. The antitumor and antibacterial properties of the new compounds were evaluated.     

Structure determination of two new indole‐diterpenoids from Penicillium sp. CM‐7 by NMR spectroscopy

Two new indole‐diterpenoids 4b‐deoxy‐1′‐O‐acetylpaxilline (1) and 4b‐deoxypenijanthine A (2) were isolated from the fermentation broth and the mycelia of the soil fungus Penicillium sp. CM‐7, along with three known structurally related compounds, 1′‐O‐acetylpaxilline (3), paspaline (4) and 3‐deoxo‐4b‐deoxypaxilline (5). The structures of compounds 1 and 2 were elucidated by extensive spectroscopic methods, especially 2D NMR, and their absolute configurations were suggested on the basis of the circular dichroism spectral analysis and the NOESY data. Copyright © 2014 John Wiley & Sons, Ltd.