Polychlorinated hydrocarbon motifs have been synthesized in enantiomerically pure forms by means of nucleophilic multiple chlorinations of chiral epoxides, which stereospecifically incorporate halogen atoms into oxygenated molecular scaffolds. The present study demonstrates the scope of the N-chlorosuccinimide (NCS)/organophosphine reagent system that forms multiple sp(3)C-Cl bonds in a regularly repeating pattern with proper stereochemical configurations and evaluates its applicability to various epoxides having elaborate structures. It is noteworthy that tetrachlorinated motifs are produced in one step from bisepoxides by using NCS/Ph(3)P. Furthermore, Ph(2)PCl used in combination with NCS has been found to serve as a potentially useful alternative to NCS/Ph(3)P, especially for promoting dichlorination reactions of alkenyl-substituted epoxides.
The enantioselective total synthesis of (+)-hexachlorosulfolipid, a cytotoxin found in the Adriatic mussel Mytilus galloprovincialis, is described. The unique chlorinated hydrocarbon motif of the lipid is successfully furnished by a series of dichlorination reactions of chiral epoxides with chlorophosphonium reagent generated in situ from Ph(3)P/NCS. The present total synthesis has allowed the confirmation of the absolute configuration of the natural cytotoxic (+)-hexachlorosulfolipid originally proposed by Fattorusso, Ciminiello, and co-workers.
RoFSO (Radio on Free Space Optics) system is a system to confine several radio signals in an optical wireless signal as RF subcarriers, and transmits them to air. This system can transmit radio signals through the air without using RF wave and construct virtual free radio frequency space. However, if the optical wireless link is interrupted with the obstacle, the shadowing will deteriorate the signal quality. Hence this paper proposes a method to establish virtual distributed antenna system using convex mirrors. Computer simulation shows that shadowing problem is solved and the received signal quality at a mobile terminal can be improved compared with the single antenna method.Index Terms -Radio on Free Space Optics (RoFSO), Radio on Fiber (RoF), unrepeatered distributed antenna system, convex mirror, indoor optical wireless communication system.
Halogen compounds P 0030Enantiocontrolled Synthesis of Polychlorinated Hydrocarbon Motifs: A Nucleophilic Multiple Chlorination Process Revisited. -Treatment of epoxides with NCS/ PPh3 or NCS/ Cl-PPh2 allows facile and highly stereoselective access to di-and tetrachlorinated compounds. -(YOSHIMITSU*, T.; FUKUMOTO, N.; TANAKA, T.; J. Org. Chem. 74 (2009) 2, 696-702; Grad. Sch. Pharm. Sci., Osaka Univ., Suita, Osaka 565, Japan; Eng.) -Jannicke 21-050
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