Asymmetric synthesis of optically active halohydrins and oxiranes by enantioselective reduction of prochiral α-haloketones with chirally modified lithium borohydride
作者:Kenso Soai、Takashi Yamanoi、Hitoshi Hikima
DOI:10.1016/0022-328x(85)87441-6
日期:1985.7
Prochiral α-haloketones are reduced enantioselectively with the asymmetric reducing system lithium borohydride N,N′-dibenzoylcystine /t-butyl alcohol to give the corresponding halohydrins with up to 86% enantiomeric excess, some of which are converted to optically active oxiranes.
anti-Prelog microbial reduction of aryl α-halomethyl or α-hydroxymethyl ketones with Geotrichum sp. 38
作者:Zhi-Liang Wei、Zu-Yi Li、Guo-Qiang Lin
DOI:10.1016/s0040-4020(98)00796-0
日期:1998.10
Reduction of aryl α-halomethyl ketones 5a-d and 7a-h and α-hydroxymethyl ketones 10a-b by Geotrichum sp. 38 affording mostly the anti-Prelog alcohols was reported and the stereoselectivities of the reductiveproducts were discussed.
Convenient, in Situ Generation of Anhydrous Hydrogen Iodide for the Preparation of α-Glycosyl Iodides and Vicinal Iodohydrins and for the Catalysis of Ferrier Glycosylation
作者:Stephanie M. Chervin、Paolo Abada、Masato Koreeda
DOI:10.1021/ol991312d
日期:2000.2.1
[reaction: see text] Anhydrous hydrogen iodide is generated in situ by the reaction of solid iodine and a thiol. The HI thus generated has been employed for the efficient preparation of alpha-glycosyl iodides and vicinal iodohydrins from the corresponding glycosyl acetates and epoxides, respectively, and for Ferrier glycosylation of alcohols and thiols.
The reaction of epoxides with lithiumhalides was efficiently promoted on the surface of silica gel in the absence of any solvent to give the corresponding β-halohydrins. The reactivity of lithiumhalides was shown to follow the order LiI> LiBr>> LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand, a similar reaction