39477-88-8Relevant academic research and scientific papers
Rhenium-Catalyzed Regioselective ortho-Alkenylation and [3 + 2 + 1] Cycloaddition of Phenols with Internal Alkynes
Murai, Masahito,Yamamoto, Masaki,Takai, Kazuhiko
supporting information, p. 3441 - 3445 (2019/05/10)
An operationally simple and direct rhenium-catalyzed ortho-alkenylation (C-alkenylation) of unprotected phenols with alkynes was developed. The protocol provided ortho-alkenylphenols exclusively, and formation of para- or multiply alkenylated phenols and
Mechanistic Insights into Rhenium-Catalyzed Regioselective C-Alkenylation of Phenols with Internal Alkynes
Murai, Masahito,Yamamoto, Masaki,Takai, Kazuhiko
supporting information, p. 15189 - 15197 (2019/11/16)
A (μ-aryloxo)rhenium complex was isolated and confirmed as a key precatalyst for rhenium-catalyzed ortho-alkenylation (C-alkenylation) of unprotected phenols with alkynes. The reaction exclusively provided ortho-alkenylphenols; the formation of para or multiply alkenylated phenols and hydrophenoxylation (O-alkenylation) products was not observed. Several mechanistic experiments excluded a classical Friedel–Crafts-type mechanism, leading to the proposed phenolic hydroxyl group assisted electrophilic alkenylation as the most plausible reaction mechanism. For this purpose, the use of rhenium, a metal between the early and late transition metals in the periodic table, was key for the activation of both the soft carbon–carbon triple bond of the alkyne and the hard oxygen atom of the phenol, at the same time. ortho-Selective alkenylation with allenes also provided the corresponding adducts with a substitution pattern different from that obtained by the addition reaction with alkynes.
Rhodium(III)-catalyzed ortho alkenylation of n-phenoxyacetamides with n-tosylhydrazones or diazoesters through C-H activation
Hu, Fangdong,Xia, Ying,Ye, Fei,Liu, Zhenxing,Ma, Chen,Zhang, Yan,Wang, Jianbo
, p. 1364 - 1367 (2014/03/21)
A coupling reaction of N-phenoxyacetamides with N-tosylhydrazones or diazoesters through RhIII-catalyzed C-H activation is reported. In this reaction, ortho-alkenyl phenols were obtained in good yields and with excellent regio- and stereoselectivity. Rh-c
Highly enantioselective hydrogenation of styrenes directed by 2′-hydroxyl groups
Wang, Xiang,Guram, Anil,Caille, Seb,Hu, Jack,Preston,Ronk, Michael,Walker, Shawn
, p. 1881 - 1883 (2011/05/15)
A new synthetic strategy that turns styrene-type olefins into excellent substrates for Rh-catalyzed asymmetric hydrogenation by installing a 2′-hydroxyl substituent is described. This methodology accommodates trisubstituted olefinic substrates in various E/Z mixtures, leading to valuable benzylic chiral compounds including (R)-tolterodine. It is also demonstrated that the 2′-hydroxyl groups could be readily removed in high yield without loss of ee from the products. Thus, this technology represents an attractive alternative to the Ir(P-N) catalyst system for the asymmetric hydrogenation of unfunctionalized olefins.
