Metal Trifluoromethanesulfonate‐Catalyzed Regioselective Reductive Ring Opening of Benzylidene Acetals

A systematic study of various metal trifluoromethanesulfonates as efficient catalysts in the regioselective reductive ring opening of benzylidene acetals is described, including the effects of solvents, reducing agents, and temperature. These catalysts are found to be effective in cleaving the 4,6‐O‐acetal rings of hexopyranosides at either O4 or O6, respectively. When used in conjunction with a 1 M solution of BH₃·THF in THF without extra addition of any solvent, it affects the ring fission at the O6 position to generate the corresponding primary alcohols, whereas O4‐opening takes place in acetonitrile in the presence of dimethylethylsilane as the reductant leading to the secondary hydroxyl derivatives in high selectivity and yields. These methodologies can be applied to a wide range of substrates containing various functional groups.     

Supramolecular assembly of gold(I) complexes of diphosphines and N,N'-bis-4-methylpyridyl oxalamide

We report herein the supramolecular assembly and spectroscopic and luminescent properties of gold(I) complexes of diphosphines (dppm [bis(diphenylphosphino)methane], dppp [1,3-bis(diphenylphosphino)propane], and dpppn [1,5-bis(diphenylphosphino)pentane]) and N,N'-bis-4-methylpyridyl oxalamide (L). The dppm and dppp cases form the rectangular structures, [dppm(Au(2))L](2)(ClO(4))(4) and [dppp(Au(2))L](2)(ClO(4))(4), with four gold(I) ions at the corners, as well as two L and two dppm or dppp ligands as edges, featuring 38- and 42-membered rings for the former and the latter, respectively. Remarkably, the packing of the dppp complexes shows interesting one-dimensional rectangular channels in the solid state, most likely due to intermolecular pi...pi interactions. The dpppn complex has been structurally characterized as a one-dimensional coordination polymer, {[(dpppn)(3.5)(Au(7))L(3.5)](PF(6))(7)}. The absorptions and emissions of the compounds are in general due to intraligand transitions, but aurophilic or pi...pi interactions could also make partial contributions. The dipyridyl amide system with the amides incorporated into the bridging ligands as well as the one-dimensional rectangular channels in the solid state for the dppp-based rectangle make this a promising family of metal-containing cyclic peptides in crystal engineering and molecular-recognition studies.     

Using FSBT technique with Rough Set Theory for personal investment portfolio analysis

This study proposes a novel Forward Search and Backward Trace (FSBT) technique based on Rough Set Theory to improve data analysis and extend the scope of observations made from sample data to solve personal investment portfolio problems. Rough Set Theory mathematically classifies data into class sets. The class set with the most objects may generate one decision rule. The rules generated from RST are rough and fragmented, that are very difficult to interpret the information. An empirical case is used to generate more than 85 rules by the RST method in comparison with FSBT method which only generated 14 rules. This result can show our proposed method is better than traditional RST method based on class sets that contain the most objects. Much of human knowledge is described in natural language. It is a very important thing to convert information from computer databases into normal human language. Sample data taken from features with the same backgrounds are used to compile different portfolios that investment companies and investment advisors can employ to satisfy the investor’ needs. The method not only can provide decision-making rules, but also can offer alternative strategies for better data analysis. We believe that the FSBT technique can be fully applied in research on investment marketing.     

Quantum Private Communication with an Anonymous Sender

We propose a new quantum private communication protocol, in which the anonymity of the sender and the privacy of the quantum information are perfectly protected except with exponentially small probability. Furthermore, this protocol uses single particles to construct anonymous entanglement instead of multipartite entangled states, and thus it reduces quantum resources compared with the previous work.     

A New Approach for Visual Cryptography

Visual cryptography is to encrypt a secret image into some shares (transparencies) such that any qualified subset of the shares can recover the secret visually. The conventional definition requires that the revealed secret images are always darker than the backgrounds. We observed that this is not necessary, in particular, for the textual images.In this paper, we proposed an improved definition for visual cryptography based on our observation, in which the revealed images may be darker or lighter than the backgrounds. We studied properties and obtained bounds for visual cryptography schemes based on the new definition. We proposed methods to construct visual cryptography schemes based on the new definition. The experiments showed that visual cryptography schemes based on our definition indeed have better pixel expansion in average.     

1,2,4-苯三甲酸铜二维网状配合物的合成及结构表征(英)

在室温下,MnSO₄·H₂O和1,2,4-苯三甲酸(H₃BTC)反应得到化合物[Mn(H₂BTC)₂(H₂O)₄]·2H₂O (1),化合物1和CuSO₄·5H₂O反应得到化合物[Cu(HBTC)(H₂O)_1.5]·H₂O (2)。化合物1是一个单核分子化合物。在化合物1中,每个锰离子和两个H₂BTC^－离子及四个水分子配位。化合物2中,每个铜离子和三个HBTC^2－及两个水分子配位,其中的一个水分子起桥联作用从而形成二维网状结构。     

Synthesis and Evaluation of α-Methylidene-γ-butyrolactone bearing flavone and xanthone moieties

In a search for inhibitors of platelet aggregation, a number of α-methylidene-γ-butyrolactones 5 and 6 bearing flavone or xanthone moieties, respectively, were synthesized and evaluated for their antiplatelet activity against thrombin(Thr)-, arachidonic-acid(AA)-, collagen(Col)?, and platelet-activating-factor(PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 7-hydroxyflavone ( 1 ) or 3-hydroxyxanthone ( 2 ) via O-alkylation (→ 3 and 4 , resp.) and Reformatsky-type condensation (Scheme). Most of the flavone-containing α-methylidene-γ-butyrolactones 5a – d showed potent antiplatelet effects on AA- and Col-induced aggregation, while xanthone derivatives 6c – e were found to have the same pharmacological profile than aspirin in which only AA-induced aggregation was inhibited (Table 1). However, 6c – e were approximately three to ten times more potent than aspirin (Table 2). For the vasorelaxing effects, 5a was the only compound which exhibited significant inhibitory activity on the high-K⁺ medium, Ca²⁺-induced vasoconstriction (Table3). Both 5a and 6a , with an aliphatic Me substituent at C(γ) of the lactone, were active against norepinephrine-induced phasic and tonic constrictions while their γ-aryl-substituted counterparts 5b – f and 6b – f were inactive.     

Synthesis and Evaluation of 2-{[(2-Oxo-1H-quinolin-8-yl)oxy]methyl}-Substituted α-Methylidene-γ-butyrolactones

O-Alkylation of 8-hydroxy-1H-quinolin-2-one ( 1 ) afforded 8-(2-oxopropoxy)-1H-quinolin-2-one ( 2 ) which was immediately cyclized to form the tricyclic 2,3-dihydro-3-hydroxy-3-methyl-5H-pyrido[1,2,3-de][1,4]benzoxazine,-5-one ( 3). The Reformatsky-type condensation of 3 furnished antiplatelet 8-[(2,3,4,5-tetrahydro-2-methyl-4-methylidene-5-oxofuran-2-yl)melhoxy]-1H-quinolin-2-one ( 4 ). Its counterparts 7a – f , Ph-substituted at C(2) of the furan ring, were obtained from 1 via alkylation and the Reformatsky-type condensation. Although compound 4 was less active against platelet aggregation than 7a – f , it was the only compound which exhibited significant inhibitory activity on high-K⁺ medium, Ca²⁺-induced vasoconstriction and was more active than most of its Ph-substituted counterparts against norepinephrine-induced vasoconstrictions.     

Three New Cadinene Derivatives from Xenia Puerto‐Galerae

Chromatographic investigation of an acetone extract of the octocoral Xenia puerto‐galerae afforded three new cadinene sesquiterpenes; 8‐epi‐xenitorin A ( 1 ), 10‐epi‐xenitorin C ( 2 ), and 7‐isopropenyl‐4,10‐dimethyl‐2,3,4,5‐tetrahydronaphthalene ( 3 ), in addition to four known cadinene analogs ( 4 , 11–13 ) and six xenicanes ( 5–10 ). The structures were elucidated through spectroscopic analysis, especially 2D NMR. A biogenetic pathway of 1–3 and analogs was proposed.