50447-25-1Relevant academic research and scientific papers
Chelation-controlled diastereoselective reduction of α-fluoroketones
Mohanta, Pramod K.,Davis, Todd A.,Gooch, Jeremy R.,Flowers II, Robert A.
, p. 11896 - 11897 (2005)
The effect of Ti-based Lewis acids on the reduction of α-fluoropropiophenone was examined to determine whether chelation control could be used to direct the diastereoselectivity of conversion to an α-fluoro alcohol. Pretreatment of α-fluoropropiophenone with TiCl4 followed by reduction with LiBH4 in diethyl ether or methylene chloride provided the syn diastereomer predominantly, while use of Ti(OiPr)4 under identical conditions provided the anti diastereomer as the major product. The products are consistent with a chelation-controlled mechanistic pathway in the former reduction and a nonchelation pathway in the latter case. Detailed 1H, 13C, and 19F NMR studies were consistent with chelation between TiCl4 and α-fluoropropiophenone under the reaction conditions utilized in this study. Reduction of other α-fluoroketones in the presence of TiCl4 also provided a high degree of diastereoselectivity in the conversion to α-fluoro alcohols, showing the generality of this approach. Copyright
Open-Shell Fluorination of Alkyl Bromides: Unexpected Selectivity in a Silyl Radical-Mediated Chain Process
Lovett, Gabrielle H.,Chen, Shuming,Xue, Xiao-Song,Houk,MacMillan, David W. C.
, p. 20031 - 20036 (2019/12/27)
We disclose a novel radical strategy for the fluorination of alkyl bromides via the merger of silyl radical-mediated halogen-atom abstraction and benzophenone photosensitization. Selectivity for halogen-atom abstraction from alkyl bromides is observed in the presence of an electrophilic fluorinating reagent containing a weak N-F bond despite the predicted favorability for Si-F bond formation. To probe this surprising selectivity, preliminary mechanistic and computational studies were conducted, revealing that a radical chain mechanism is operative in which kinetic selectivity for Si-Br abstraction dominates due to a combination of polar effects and halogen-atom polarizability in the transition state. This transition-metal-free fluorination protocol tolerates a broad range of functional groups, including alcohols, ketones, and aldehydes, which demonstrates the complementary nature of this strategy to existing fluorination technologies. This system has been extended to the generation of gem-difluorinated motifs which are commonly found in medicinal agents and agrochemicals.
Reaction of Xenon Difluoride with Indene in Aqueous 1,2-Dimethoxyethane and Tetrahydrofuran
Shellhamer, Dale F.,Carter, David L.,Chiaco, Michael Chua,Harris, Tyler E.,Henderson, Rodney D.,et al.
, p. 401 - 403 (2007/10/02)
Xenon difluoride (XeF2) reacts with indene in 1,2-dimethoxyethane-water (90:10) to give cis- and trans-2-fluoro-1-hydroxyindans.Our data indicate that neither xenon oxide (XeO) nor hydroxyxenon fluoride (HOXeF) is an intermediate in this reaction even though XeO is a suspected intermediate from aqueous hydrolysis of XeF2.
