A Protecting-Group-Free Synthesis of (−)-Salvinorin A

A concise enantioselective total synthesis of the neoclerodane diterpene (−)-salvinorin A is reported. The stereogenic center at C-12 was installed by catalytic asymmetric propargylation with excellent enantioselectivity, and the remaining six stereogenic centers were set up highly diastereoselectively under substrate control. As for our previous synthesis of racemic salvinorin A, two intramolecular Diels-Alder reactions were applied to generate the tricyclic core. A chemoselective Mitsunobu inversion of a syn 1,2-diol allowed for further streamlining of the original reaction sequence by two steps. Overall, (−)-salvinorin A was synthesized in only 16 steps starting from 3-furaldehyde with 1.4 % total yield. Furthermore, an alternative intramolecular Diels-Alder strategy employing a 2-bromo-1,3-diene moiety was investigated.     

A Novel Fortunate A from Cryptomerica fortunei

A novel compound, named fortunate A, was isolated from the ethanol extract of the stem bark of Cryptomerica fortunei. Its structure was established on the basis of the spectral evidences including 1D and 2D NMR spectrum.     

A Taxatetraene from Microbial Transformation of Sinenxan A

Sinenxan A [2α, 5α, 10β, 14β-tetraacetoxytaxa-4(20), ll-diene, 1] was biotransformed by a filamentous fungus, Aspergillus niger JCM 5546, and an unusual taxatetraene [2α,5α-acetoxytaxa-4(20), 10(11), 12(18), 13(14)-tetraene, 2], together with two known products,10β-deacetyl sinenxan A (3) and 10β, 14β-dideacetyl sinenxan A (4) were produced.     

Total Synthesis of Illisimonin A and Merrilactone A

Illicium sesquiterpenes are a large family of biologically active secondary metabolites isolated from Illicium species of plants and are well-known for their activity of neurite outgrowth in cultured neurons. Herein, we propose a comprehensive biosynthetic pathway for illicium sesquiterpenes and report a synthetic route to illisimonin A and merrilactone A based on it. We think that the carbon scaffolds of most of the illicium sesquiterpenes could be synthesized from a dicarbonyl derivative of allo-cedrane through retro-Dieckmann condensation, oxidative cleavage and aldol reaction at suitable oxidation states in Nature. The common intermediate for illisimonin A and merrilactone A similar to the dicarbonyl derivative of allo-cedrane was assembled with up to 82 % ee by an asymmetric intramolecular desymmetrizing reductive Heck reaction by the use of a new type of chiral phosphine ligand. The syntheses of illisimonin A and merrilactone A supported the key transformations of the proposed biosynthetic pathway.     

A NEW SAPONIN, HAINANEOSIDE A FROM MARSDENIA HAINANENSIS

Ａ　ＮＥＷ　ＳＡＰＯＮＩＮ，ＨＡＩＮＡＮＥＯＳＩＤＥ　Ａ　ＦＲＯＭ　ＭＡＲＳＤＥＮＩＡ　ＨＡＩＮＡＮＥＮＳＩＳ￥ＢａｏＸｉａＭＡ；ＴｉａｎＺｈｅｎｇＦＡＮＧ（ＤｅｐａｒｔｍｅｎｔｏｆＰｈａｒｍａｃｙ，ＴｏｎｇｉｉｎＨｏｓｐｉｔａｌ，ＴｏｎｇｊｉＭｅｄ...     

CLEMOCHINENOSIDE A, A MACROCYCLIC COMPOUND FROM CLEMATIS CHINENSIS

The structure of a new macrocyclic compound, clemochinenoside A obtained from Clematis chinensis was identified by NMR, FAB-MS, NOE and chemical hydrolysis.     

Saluenolide A,A Novel Eremophilanolide from Senecio saluenensis

From Senecio saluenensis, a novel eremophilanolide Saluenolide A was isolated. Its structure was elucidated by 2D-NMR technique and X-ray diffraction.     

A new structural model of Aβ40 fibrils

The amyloid fibrils of beta-amyloid (Aβ) peptides play important roles in the pathology of Alzheimer's disease. Comprehensive solid-state NMR (SSNMR) structural studies on uniformly isotope-labeled Aβ assemblies have been hampered for a long time by sample heterogeneity and low spectral resolution. In this work, SSNMR studies on well-ordered fibril samples of Aβ(40) with an additional N-terminal methionine provide high-resolution spectra which lead to an accurate structural model. The fibrils studied here carry distinct structural features compared to previous reports. The inter-β-strand contacts within the U-shaped β-strand-turn-β-strand motif are shifted, the N-terminal region adopts a β-conformation, and new inter-monomer contacts occur at the protofilament interface. The revealed structural diversity in Aβ fibrils points to a complex picture of Aβ fibrillation.     

EURYCARPIN A,A NEW ISOFLAVONE FROM GLYCYRRHIZA EURYCARPA

ＥＵＲＹＣＡＲＰＩＮ Ａ， Ａ ＮＥＷ ＩＳＯＦＬＡＶＯＮＥ ＦＲＯＭ ＧＬＹＣＹＲＲＨＩＺＡ ＥＵＲＹＣＡＲＰＡ￥ＹｕＭｅｉＺＨＡＮＧ；ＸｕＤｏｎｇＸＵ；ＢｉＨｕａｎｇＨＵ；ＱｉｎＬＩＵ；ＣｕｉＹｉｎｇＨＯＵ；ＹｏｎｇＬｏｎｇＬＩＵａｎｄＪｕｎＳｈ...     

STELLADELIN A, A NEW CYCLOPEPTIDE FROM STELLARIA DELAVAYI

ＳＴＥＬＬＡＤＥＬＩＮ　Ａ，Ａ　ＮＥＷ　ＣＹＣＬＯＰＥＰＴＩＤＥ　ＦＲＯＭ　ＳＴＥＬＬＡＲＩＡ　ＤＥＬＡＶＡＹＩＹｕＲｕｉＺＨＡＯ；ＪｕｎＺＨＯＵ；ＸｉａｎｇＫａｉＷＡＮＧ；ＨｏｕＭｉｎｇＷＵ；ＸｉａｏＬｉｎＨＵＡＮＧ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｄ...     

A?rogengas

Ohne Zusammenfassung     

A?roskop

Ohne Zusammenfassung     

Dissectol A,A Novel Monoterpene Glycoside from Incarvillea dissectifoliola

Dissectol A,a novel monoterpene glycoside was isolated from the methanol part of the 95% EtOH extract of Incarvillea dissecfoliola and its structure was determined by 1D and 2D NMR data.     

A stereocontrolled total synthesis of (±)-saframycin A

A thirteen-step total synthesis of (±)-saframycin A from a tricyclic lactam intermediate is described. The key step of this total synthesis is the stereocontrolled construction of a pentacyclic saframycin framework via a modified Pictet-Spengler type cyclization generating a bis-carboxylic acid ester derivative, followed by decarboxylation. The cytotoxicity profiles are also presented.     

乙烯基A2A″电子态的振转分析

通过193 nm光解丁烯酮分子产生乙烯基自由基(•C2H3). 经射流冷却后, 以另一束可调谐激光光解•C2H3, 生成的氢原子碎片经共振增强多光子电离(REMPI)过程, 记录氢离子信号随光解波长变化, 得到21180~21320 cm-1范围内乙烯基 A2A″(µ′5,6,8=1)←X2A′(µ″=0)跃迁的振转光谱. 结合量化计算和光谱拟合, 对该段光谱进行了细致的振转分析, 确定了各振动谱带位置, 识别了其中主要的转动跃迁. 由光谱拟合得到各振动能级的预解离寿命, 讨论了其与振动模式及激发转动量子数的依赖关系, 证实了理论预测的乙烯基A2A″电子态的面内解离机制.     

EXCIPLEX FORMATION OF A POLYESTER WITH A TEREPHTHALATE MAIN CHAIN HAVING A PENDANT N, N-DIMETHYLAMINO GROUP

The fluorescence behaviours of a new polymer poly [oxy-2 (4-N, N-dimethylaminobenzyl) propane-1 , 3-diyloxy-terephthaloyl] (Ⅰ) in solution were studied. Inter-and intra -molecular exciplex is formed between the singlet excited state of N, N- dimethylanilino group (abbreviated to DMA) and the ground state of terephthalate group (abbreviated to TP). The intensity ratio of the long wavelength exciplex fluorescence to the short wavelength emission of DMA group is used as an index for the inter-and intra-molecular interaction of chromophores. The results are compared with model polymer polyoxy-2-(4-N ,N-dimethylaminobenzyl) propanc-1 , 3-diyloxyadipoyl (Ⅱ), model monomer compound 4-N, N-dimethylaminobenzylmethyl terephthalate(Ⅲ) and diethyl 2-( 4-N, N-dimethylaminobenzyl) malonate (Ⅳ). Polymer association derived by electron donor and acceptor interaction (EDA) is further verified as a key role in the interpolymer exciplex formation . The fluorescence decay time of (Ⅰ) and monomer (Ⅲ) are measured in solutions.     

SYNTHESIS OF ANALOGUES OF HUPERZINE A 4．THE PREPARATION OF A PYRIMIDONE ANALOGUE OF HUPERZINE A

ＳＹＮＴＨＥＳＩＳＯＦＡＮＡＬＯＧＵＥＳＯＦＨＵＰＥＲＺＩＮＥＡ４．ＴＨＥＰＲＥＰＡＲＡＴＩＯＮＯＦＡＰＹＲＩＭＩＤＯＮＥＡＮＡＬＯＧＵＥＯＦＨＵＰＥＲＺＩＮＥＡ￥ＹｕｎＬｏｎｇＬＩ；ＸｕＣｈａｎｇＨＥａｎｄＤｏｎｇＬｕＢＡＩ（ＳｈａｎｇｈａｉＩｎｓ...     

DUCHESIDE A,A NEW ELLAGIC GLYCOSIDE FROM DUCHESNEA INDICA FOCKE

ＤＵＣＨＥＳＩＤＥＡ，ＡＮＥＷＥＬＬＡＧＩＣＧＬＹＣＯＳＩＤＥＦＲＯＭＤＵＣＨＥＳＮＥＡＩＮＤＩＣＡＦＯＣＫＥ￥ＬｉａｎｇＹＥａｎｄＪｕｎＳｈａｎＹＡＮＧ（ＩｎｓｉｔｕｔｅｏｆＭｅｄｉｃｉｎａｌＰｌａｎｔＤｅｖｅｌｏｐｍｅｎｔＣｈｉｎｅｒｅＡｃａｄｅ...