Rhenium-Catalyzed Regioselective <i>ortho</i>-Alkenylation and [3 + 2 + 1] Cycloaddition of Phenols with Internal Alkynes
作者:Masahito Murai、Masaki Yamamoto、Kazuhiko Takai
DOI:10.1021/acs.orglett.9b01214
日期:2019.5.3
(C-alkenylation) of unprotected phenols with alkynes was developed. The protocol provided ortho-alkenylphenols exclusively, and formation of para- or multiply alkenylated phenols and hydrophenoxylation (O-alkenylation) products were not observed. The [3 + 2 + 1] cycloaddition of phenols and two alkynes via ortho-alkenylation was also demonstrated, in which the alkynes functioned as both two- and one-carbon
Highly Enantioselective Hydrogenation of Styrenes Directed by 2′-Hydroxyl Groups
作者:Xiang Wang、Anil Guram、Seb Caille、Jack Hu、J P. Preston、Michael Ronk、Shawn Walker
DOI:10.1021/ol200422p
日期:2011.4.1
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.