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We report studies on radical-initiated fragmentations of model 1,5-dideoxyhomoribofuranose derivatives with bromo, chloro, and tosyloxy substituents on C2. The effects of stereochemical inversion at C2 were probed with the corresponding arabino epimers. In all cases, the elimination of bromide, chloride, and tosylate anions occurred when the 3-hydroxyl group was unprotected. The isolation of deuterium-labeled furanone products established heterolytic cleavage followed by the transfer of deuterium from labeled tributylstannane. In contrast, 3-O-methyl derivatives underwent the elimination of bromine or chlorine radicals to give the 2,3-alkene with no incorporation of label in the methyl vinyl ether. More drastic fragmentation occurred with both of the 3-O-methyl-2-tosyloxy epimers to give an aromatized furan derivative with no deuterium label. Contrasting results observed with the present anhydroalditol models relative to our prior studies with analogously substituted nucleoside models have demonstrated that insights from biomimetic chemical reactions can provide illumination of mechanistic pathways employed by ribonucleotide reductases (RNRs) and the MoaA enzyme involved in the biosynthesis of molybdopterin.

This work focuses on developing a complete non-linear dynamic model comprising entirely kinematic and hydrodynamic effects of Carangiform locomotion based on the Lagrange approach by adapting the parameters and behaviors of a real carp. In order to imitate biological features, swimming patterns of a real carp for forward, turning and up-down motions are analyzed by using the Kineova 8.20 software. The proportional optimum link lengths according to actual size, swimming speed, flapping frequency, proportional physical parameters and different swimming motions of the real carp are investigated with the designed robotic fish model. Three-dimensional (3D) locomotion is evaluated by tracking two trajectories in a MATLAB environment. A Reaching Law Control (RLC) approach for inner loop (Euler angles-speed control) and a guidance system for the outer loop (orientation control) are proposed to provide an effective closed-loop control performance. In order to illustrate the 3D performance of the proposed closed loop control system in a virtual reality platform, the designed robotic fish model is also implemented using the Virtual Reality Modeling Language (VRML). Simulation and experimental analysis show that the proposed model gives us significant key solutions to design a fish-like robotic prototype.