Zinc–gold cooperative catalysis for the direct alkynylation of benzofurans
نویسندگان
چکیده
The direct alkynylation of benzofurans was achieved for the first time using the hypervalent iodine reagent 1-[(triisopropylsilyl)ethynyl]-1,2-benziodoxol-3(1H)-one (TIPS-EBX) based on the cooperative effect between a gold catalyst and a zinc Lewis acid. High selectivity was observed for C2-alkynylation of benzofurans substituted with alkyl, aryl, halogen and ether groups. The reaction was also successful in the case of the more complex drug 8-methoxypsoralen (8-MOP).
منابع مشابه
Electrophilic alkynylation: the dark side of acetylene chemistry.
In addition to the well-established nucleophilic alkynylation, the use of electrophilic alkynes can expand tremendously the scope of acetylene transfer reactions. The use of metal catalysis has recently led to a rebirth of this research area. Halogenoalkynes, hypervalent alkynyliodoniums, acetylene sulfones and in situ oxidized terminal acetylenes are the most often used reagents for electrophi...
متن کاملChemoselective reductive alkynylation of tertiary amides by Ir and Cu(i) bis-metal sequential catalysis.
We report herein a convenient and versatile method for the direct reductive alkynylation of tertiary amides to give propargylic amines through sequential Ir-catalysed hydrosilylation-Cu(i)-catalysed alkynylation. The reactions proceed chemoselectively at the amide group in the presence of several sensitive functional groups including the very reactive aldehyde group on either the amide or the a...
متن کاملCombining Zn Ion Catalysis with Homogeneous Gold Catalysis: An Efficient Annulation Approach to N-Protected Indoles.
The Fischer indole synthesis is perhaps the most powerful method for indole preparation, but it often suffers from low regioselectivities with unsymmetric aliphatic ketone substrates and strong acidic conditions and is not suitable for α,β-unsaturated ketones. In this article, we disclose an efficient synthesis of N-protected indoles from N-arylhydroxamic acids/N-aryl-N-hydroxycarbamates and a ...
متن کاملPractical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst
This paper describes the preparation of indoles, azaindoles and benzofurans in pure water by using a new heterogeneous Pd-Cu/C catalyst through a cascade Sonogashira alkynylation-cyclization sequence. Details of the optimization studies and the substrate scope are discussed. This procedure allows the preparation of heterocycles with good yields and is tolerant to a wide variety of functional gr...
متن کاملRoom-temperature decarboxylative alkynylation of carboxylic acids using photoredox catalysis and EBX reagents.
Alkynes are used as building blocks in synthetic and medicinal chemistry, chemical biology, and materials science. Therefore, efficient methods for their synthesis are the subject of intensive research. Herein, we report the direct synthesis of alkynes from readily available carboxylic acids at room temperature under visible-light irradiation. The combination of an iridium photocatalyst with et...
متن کامل