Lewis acid catalyzed halogenation of activated carbon atoms

Abstract

A practical and efficient method for halogenation of activated carbon atoms using readily available N-haloimides and a Lewis acid catalyst has been disclosed. This methodology is applicable to a range of compounds and any halogen atom can be directly introduced to the substrate. The mild reaction conditions, easy workup procedure and simple operation make this method valuable from both an environmental and preparative point of view.

Description

RELATED APPLICATIONS[0001]This application is a continuation-in-part of Patent Cooperation Treaty International Application No. PCT / US2006 / 034066, filed Aug. 31, 2006, which claims priority to U.S. provisional application Serial No. 60 / 713,904 filed Sep. 2, 2005, the entire disclosures of which are hereby incorporated by reference.BACKGROUND[0002]Halogenation of activated carbon atoms is a highly useful reaction for the synthesis of natural products and pharmaceutically important compounds. Aromatic compounds are examples of compounds with activated carbon atoms. Aryl fluorides and chlorides are found in many natural products and pharmaceutical compounds. Aryl bromides and iodides are important building blocks in organic syntheses because of their utility in carbon-carbon bond forming reactions. For example, aryl bromides and iodides are precursors to numerous organometallic species that are used in organic synthesis. Organometallic species and aryl bromides and iodides or benzyl br...

AI Technical Summary

Benefits of technology

The present invention provides methods for halogenating an activated carbon atom in the presence of a Lewis acid. This allows for the creation of functionalized elemental carbon materials with improved properties. The halogen donor can be selected from a group of compounds, and the Lewis acid can be a metal such as Zr, Fe, or Al. The resulting functionalized elemental carbon can be used as a catalyst or can be further modified by adding a functional group and a metal. The invention provides a novel way to modify the carbon atom, which can be useful in various fields such as catalysis and electronics.

Problems solved by technology

These reagents have a number of drawbacks including toxicity, high reactivity, corrosiveness, nonselectivity particularly in molecules with complex and sensitive functionality, as well as the fact that only half of the halogen in the reagent is consumed.

In addition, the reaction product mixtures arising from these reagents can lead to high levels of toxic and corrosive waste, as well as purification difficulties.

Previous attempts to employ these reagents for aromatic halogenation, however, have usually required severe reaction conditions to activate or enhance the halogenating ability of these compounds.

For example, previous attempts employed highly acidic solutions, large amounts of catalyst and / or high temperatures.

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