The coupling reaction of aryl iodides with acetylacetone or ethyl cyanoacetate under catalysis of CuI/L-proline works at relatively mild conditions to provide 3-aryl-2, 4-pentanediones and a-aryl cyanoacetates in moderate to good yields.Reaction of aryl halides with carbon nucleophiles, such as anions of active methylene compounds, is a useful tool for the preparation of substituted aromatic compounds, 1 such as 3-aryl-2,4-pentanediones and a-aryl cyanoacetates, which are very important building blocks for synthesizing various heterocycles, amino alcohols and amino acids. 2,3Among the many methods available for the a-aryl carbonyl compounds, a great deal of recent attention has focused on the development of palladium-catalyzed arylation methodology. 4 Some exciting achievements have already appeared in this field. For instance, the coupling of diethyl malonate or ethyl cyanoacetate with aryl chloride could be carried out at 70°C using certain phosphines as the ligands. 4c However, high costs and toxicity of Pd reagents and the relative ligands limit their application in industrial employment.The arylation of activated methylene compounds mediated by copper salts is a well-established process, 5 but the reaction usually requires a stoichiometric amount of copper salt unless the halides are activated by an o-carboxylate group. 6 In 1993, Miura et al. reported a coppercatalyzed arylation of malononitrile, ethyl cyanoacetate and acetylacetone using aryl iodides. 7 However, their system required harsh condition (120°C) and the substrate scope was limited. In recent years, research efforts in several laboratories have delivered a series of mild Ullmanntype methodologies based on employing some specific ligands. For examples, Buchwald and co-workers reported copper-catalyzed methods for arylation of amides, amines, N-heterocycles, hydrazides, phenols and a-aryl malonates using suitable additives such as glycol and diethylsalicyamide. 8 Ma's group discovered that L-proline and other amino acids were another type of effective ligands for copper-catalyzed coupling reactions of aryl halides with amines, N-heterocycles, sodium azide, sulfinic acid salts, phenols, and 1-alkynes. 9 Cristau and co-workers have also developed mild copper-catalyzed Narylation and C-arylation by employing chelating Schiff base Chxn-Py-Al as the ligand. 10 Stimulated by their results, we recently found that L-proline could serve as a promoter for CuI-catalyzed coupling reaction of aryl iodides with acetylacetone or ethyl cyanoacetate, giving cross-coupling products in relatively mild conditions. Herein we wish to detail our results.Initially, we used the reaction of iodobenzene with acetylacetone as a model to explore the suitable reaction conditions. It was found that under the conditions of 10 mol% CuI, 20 mol% L-proline, and 4 equivalents K 2 CO 3 in DMSO the reaction gave 3-phenyl-2,4-pentanedione in 76% yield at 90°C (Equation 1, entry 1 in Table 1). In the absence of L-proline, the reaction gave only 35% yield at 90°C (entry 2), which indicat...

The development of Internet of Things (IoT) and Mobile Edge Computing (MEC) has led to close cooperation between electronic devices. It requires strong reliability and trustworthiness of the devices involved in the communication. However, current trust mechanisms have the following issues: (1) heavily relying on a trusted third party, which may incur severe security issues if it is corrupted, and (2) malicious evaluations on the involved devices which may bias the trustrank of the devices. By introducing the concepts of risk management and blockchain into the trust mechanism, we here propose a blockchain-based trust mechanism for distributed IoT devices in this paper. In the proposed trust mechanism, trustrank is quantified by normative trust and risk measures, and a new storage structure is designed for the domain administration manager to identify and delete the malicious evaluations of the devices. Evidence shows that the proposed trust mechanism can ensure data sharing and integrity, in addition to its resistance against malicious attacks to the IoT devices.

Deployed in the monitoring environment, Wireless Sensor Network (WSN) is a measurement and control network composed of miniature and low-cost sensors with sensing, computing, and communication capabilities. The design of the Directed Dif-fusion (DD) routing protocol is one of the key problems in WSN. In order to obtain the confidentiality of sensing data and solve the unreliability of relay nodes in the existing DD routing protocols, this paper designs an Energy Trust Model (ETM) by introducing the remaining energy and trust of a node. We further propose a Trust-based Secure Directed Diffusion Rout-ing protocol (TSDDR) based on the model. The proposed protocol achieves the establishment of a credible communication path and the transmission of confidential data in WSN. Meanwhile, the balance of energy consumption and the privacy of sensing data can be ensured. The performance analysis results show that the TSDDR protocol can effectively defeat against MITM attacks and prevent the malicious nodes' impersonation. At the same time, the protocol achieves secure end-to-end anonymous communication with acceptable energy overhead and computational complexity.

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