5-Benzylidenehydantoin reacts with chlorosulfonic acid to give the corresponding p-sulfonyl chloride 1. Condensation with nucleophiles gives amino acid derivatives 2-7. Coupling reactions of some amino acid derivatives (2-6) with amino acid methyl ester hydrochloride in THF-Et3N medium using the dicyclohexylcarbodiimide method (DCC) furnish the desired dipeptidemethyl esters 8-12. The spectral data of the synthesized compounds are briefly discussed.

-Routing protocols for wireless sensor networks pay a great attention to the limited resources of the nodes. As battery lifetime is a major concern, we consider our proposed model as an effort to prolong the network lifetime in harmony with WSNs' constraints. In this paper, we study LEACH routing protocol and its performance and propose an extension to it, MA-LEACH. We introduce a mobile aggregator (MA) which is a gadget adopted to mitigate the overhead on the cluster heads (CHs). In addition, we optimize the trajectory using particle swarm optimization (PSO). Hence, we adapt the TSP problem to our protocol to determine the optimal trajectory that a mobile aggregator could travel to visit every cluster head in the network. We simulate the proposed protocol in MATLAB and the results reveal that it outperforms LEACH in network lifetime and energy consumption. Also, we compare our findings with a recent extension to the LEACH called LEACH with fuzzy descriptors and with clustered heterogeneous sensor networks (CHSNs) with a mobile sink. The simulation results show that MA-LEACH surpasses LEACH with fuzzy descriptor and CHSNs.

Routing protocols for wireless sensor networks pay a great attention to the limited resources of the nodes. In this paper, we study LEACH routing protocol and its performance and propose a new protocol, MA-LEACH. We introduce a mobile aggregator which is a gadget adopted to mitigate the overhead on the cluster heads(CHs). In addition, we optimize the trajectory using particle swarm optimization (PSO). Hence, we adapt the TSP problem to our protocol to determine the optimal trajectory that a mobile aggregator could travel to visit every cluster head in the network. We simulate the proposed protocol in MATLAB and the results reveal that it outperforms LEACH in network lifetime and energy consumption. Also, we compare our findings with a recent extension to the LEACH called LEACH with fuzzy descriptors. The simulation results show that MA-LEACH surpasses LEACH with fuzzy descriptor.