K2PtCl4/AgOTf as a Highly Active Catalyst for Hydroarylation of Propiolic Acids with Arenes

Abstract

A new and efficient K2PtCl4/AgOTf catalyst for the hydroarylation of propiolic acid was found. The hydroarylation of propiolic acids gave predominantly (Z)-cinnamic acid derivatives in high yields. The K2PtCl4/AgOTf catalyst showed a high activity to less reactive benzene.

Transition‐Metal‐Catalyzed Hydroarylation Reactions of Alkynes Through Direct Functionalization of C–H Bonds: A Convenient Tool for Organic Synthesis

“…As shown in Scheme 13, in the presence of PtCl 2 / AgOTf [10] as catalyst, mesitylene reacts with ethyl propiolate at room temperature to afford ethyl cis-trimethylcinnamate in 86 % yield after 15 h. When propiolic acid is used instead of ethyl propiolate, the yield of the desired product is improved to 94 %. Among platinum catalysts, K 2 PtCl 4 has been found to be more effective in combination with AgOTf: [11] the hydroarylation of propiolic acid with benzene proceeds effectively in the presence of K 2 PtCl 4 /AgOTf as catalyst to give cis-cinnamic acid in 54 % yield at room temperature or in 61 % yield at 40°C (Scheme 14). However, this catalyst exhibited low reactivity toward less reactive aromatic substrates and could not be applied to hydroarylation with benzene as a representative aromatic compound.…”

“…However, this catalyst exhibited low reactivity toward less reactive aromatic substrates and could not be applied to hydroarylation with benzene as a representative aromatic compound. Among platinum catalysts, K 2 PtCl 4 has been found to be more effective in combination with AgOTf: [11] the hydroarylation of propiolic acid with benzene proceeds effectively in the presence of K 2 PtCl 4 /AgOTf as catalyst to give cis-cinnamic acid in 54 % yield at room temperature or in 61 % yield at 40°C (Scheme 14). As would be expected, representative electronrich aromatic substrates give high yields of cinnamic acid derivatives in hydroarylations with this catalyst, as shown in Scheme 14.…”

Transition metals in organic synthesis: Highlights for the year 2005

“…Palladiumcatalyzed intermolecular hydroarylations alkynes using pyrroles and thiophens [789]. A platinum-silver catalyst system was used in anti-hydroarylations of 2-alkynoic acids [790]. An iridium catalyst system for hydroarylations of alkenes was reported [791].…”

Alkyne Hydroarylations with Chelating Dicarbene Palladium(II) Complex Catalysts: Improved and Unexpected Reactivity Patterns Disclosed Upon Additive Screening

“…[7b,9] The reaction is characterised by a high and quite unusual regio-and stereoselectivity: in fact, it is remarkable that the thermodynamically less favoured cis-arylalkenes are the major products. Other noble metal centres, such as platinum(II), [10] gold(I) and gold(III), [11] as well as non-noble, electrophilic metal centres (group 3, 4, 13 and 15 elements, lanthanides) [12] have been successfully employed as alternative catalysts, but their efficiency appears to be lower and/or their reaction scope narrower than that of palladium(II).…”