Stereospecific Electrophilic Fluorination of Alkylcarbastannatrane Reagents

Abstract

The introduction of fluorine atoms into organic molecules significantly changes their physical, chemical, and biological properties. Fluorinated organic compounds are used as pharmaceuticals, agrochemicals, materials, and tracers for positron emission tomography (PET). For example, the site-specific fluorination of drugs can block sites of phase I metabolism by cytochrome P450 enzymes as well as improve target-binding affinities. In view of the unique features of fluorine-containing compounds, there has been increasing interest in the development of novel methods for the synthesis of fluorinated molecules, especially the site-specific monofluorination of complex molecules. Herein, we present the enantiospecific conversion of chiral secondary alkylcarbastannatranes into alkylfluorides. Carbastannatranes were used as nucleophiles, with Selectfluor I 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 alkylcarbastannatranes were converted into alkylfluorides under mild condition by this method. Other halogenations, such as chlorination, bromination and iodination, were also applied to alkylcarbastannatranes with high enantiospecificity