Byung Hee Han

Organic sonochemistry. Ultrasound promoted coupling of chlorosilanes in the presence of lithium wire

Abstract Triorganometal chlorides, R 3 MCl (R = alkyl, aryl, M = Si, Sn) are readily coupled to form bimetallics in 42–95% yields using Li wire and ultrasound. Dihalosilanes give good yields of cyclic polysilanes.

Organic sonochemistry. Ultrasound-promoted coupling of organic halides in the presence of lithium wire

Abstract Alkyl, aromatic, benzylic and benzoyl halides have been successfully coupled in good yields using lithium wire suspended in tetrahydrofuran and ultrasound.

Organic Sonochemistry, ultrasonic acceleration of the reduction of simple and deactivated aryl halides using lithium aluminum hydride

Abstract Eleven aromatic halides are reduced in very high yields in the presence of LiAlH4 and sonic waves at 35°.

d-ribofuranosyl azides. A direct conversion of 1-O-acyl-2,3-O-isopropylidene-d-ribofuranose into d-ribofuranosyl azides

Abstract Reactions of azidotrimethylsilane with 1-O-acetyl-2,3,5-tri-O-benzoyl-β- d -ribofuranose (2), and the 1,5-di-O-p-nitrobenzoyl and 1,5-di-O-acetyl derivatives, 4 and 5 respectively, of 2,3-O-isopropylidene-β- d -ribofuranose, in the presence of the Lewis acids aluminum chloride, titanium tetrachloride, or boron trifluoride etherate were studied. All three Lewis acids readily catalyze the quantitative conversion of 2 into its β- d -ribofuranosyl azide, whereas only aluminum chloride is a suitable catalyst for conversion of 4 and 5 into their azides; boron trifluoride etherate is ineffective, and titanium tetrachloride causes partial decomposition. Contrary to the behavior of 2, which gives only the β azide, 4 and 5 give, in excellent yield, anomeric mixtures of azides in which the β azide preponderates. Although dichloromethane and acetonitrile are appropriate solvents for the reaction of 2, only acetonitrile is suitable for 4 and 5, as use of the former results in the co-production of related d -ribofuranosyl chlorides.