Synthesis of Enantioenriched Alkylfluorides by the Fluorination of Boronate Complexes
摘要:
The enantiospecific conversion of chiral secondary boronic esters into alkylfluorides is reported. Boronate complexes derived from boronic esters and PhLi were used as nucleophiles, with Selectfluor II as the electrophilic fluorinating agent, to afford alkylfluorides in short reaction times. The addition of styrene as a radical trap was found to enhance enantiospecificity. A broad range Of alkyl boronic esters were converted into alkylfluorides with almost complete enantiospecificity by this method.
A large number of fluorination methods have been developed, but the construction of a tertiary C–F bond remains challenging. Herein, we describe an efficient dehydroxylative fluorination of tertiaryalcohols with Selectfluor via the activation of a hydroxyl group by a Ph2PCH2CH2PPh2/ICH2CH2I system. Although the reagents appear to be not compatible (Selectfluor with the phosphine and I– generated in
Open-Shell Fluorination of Alkyl Bromides: Unexpected Selectivity in a Silyl Radical-Mediated Chain Process
作者:Gabrielle H. Lovett、Shuming Chen、Xiao-Song Xue、K. N. Houk、David W. C. MacMillan
DOI:10.1021/jacs.9b11434
日期:2019.12.26
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 halogenatomabstraction 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 account
Iridium-Catalyzed Allylic Fluorination of Trichloroacetimidates
作者:Joseph J. Topczewski、Timothy J. Tewson、Hien M. Nguyen
DOI:10.1021/ja2087213
日期:2011.12.7
allylic fluorination method utilizing trichloroacetimidates in conjunction with an iridium catalyst has been developed. The reaction is conducted at room temperature under ambient air and relies on Et(3)N·3HF reagent to provide branched allylic fluorides with complete regioselectivity. This high-yielding reaction can be conducted on a multigram scale and shows considerable functional group tolerance