First Catalyzed Hydration of Halo­alkynes by a Recyclable Catalytic ­System

Abstract

The hydration of haloalkynes to give α‐halomethyl ketones was achieved based on a combination of a Cu(OAc)2 catalyst and a TFA (trifluoroacetic acid) promoter. This is the first synthesis of chloro/bromo/iodo methyl ketones through a hydration reaction catalyzed by a recyclable catalytic system. The catalytic system has a wide substrate scope and excellent chemoselectivity, and the procedure can also be scaled up.

Au(I)‐Catalyzed Hydration of 1‐Iodoalkynes Leading to α‐Iodoketones

“…[ 19 ] Recently, two new alternatives to gold catalysis have expanded the available protocols for hydration chemistry. While these approaches report the use of simple Ag(I) [ 20 ] and Cu(II) [ 21 ] salts, important drawbacks still remain, such as the use of a non‐innocent and strongly‐acidic solvent (trifluoroacetic acid). [ 22 ] More recently, the use of 10 mol‐% In(OTf) 3 in AcOH at 100 °C has also proven useful for the hydration of 1‐iodoalkynes, [ 23 ] although displaying similar drawbacks to those reported in previous protocols.…”

Discovery and Comparison of Homogeneous Catalysts in a Standardized HOT‐CAT Screen with Microwave‐Heating and qNMR Analysis: Exploring Catalytic Hydration of Alkynes

“…of H 2 O), i. e., under conditions that favor hidden Brønsted acid catalysis and which may not be specific to copper . A less acidic copper catalyst (Cu(OAc) 2 ) used trifluoroacetic acid as reaction medium and was limited to haloalkyne substrates . Still other systems with CuCl/CuBr included aniline as co‐catalyst for hydroamination‐hydrolysis of internal alkynes, or require irradiation with blue LED′s over 12 h, and were limited to aryl‐alkynes .…”

Metal-Catalyzed Synthesis and Transformations of β-Haloenol Esters

“…In line with this, we would like to mention that efficient protocols for the hydration of haloalkynes RC≡CX into α-halomethyl ketones RC(=O)CH 2 X employing catalytic systems composed of AgF/CF 3 to proceed selectively since, in the presence of water, hydrolysis of intermediate G readily takes place leading to the corresponding α-halomethyl ketones 23 [64,66,67]. In line with this, we would like to mention that efficient protocols for the hydration of haloalkynes RC≡CX into α-halomethyl ketones RC(=O)CH2X employing catalytic systems composed of AgF/CF3CO2H [68], In(OTf)3/CH3CO2H [69] and Cu(OAc)2•H2O/CF3CO2H [70] have been described, in which hydrolysis of a β-haloenol acetate or trifluoroacetate intermediate (RC(O2CR´)=CHX; R´ = CH3 or CF3) has been proposed as the most likely reaction pathway.…”