Strategies towards potent trypanocidal drugs: Application of Rh-catalyzed [2 + 2 + 2] cycloadditions, sulfonyl phthalide annulation and nitroalkene reactions for the synthesis of substituted quinones and their evaluation against Trypanosoma cruzi
作者:James M. Wood、Nishikant S. Satam、Renata G. Almeida、Vinicius S. Cristani、Dênis P. de Lima、Luiza Dantas-Pereira、Kelly Salomão、Rubem F.S. Menna-Barreto、Irishi N.N. Namboothiri、John F. Bower、Eufrânio N. da Silva Júnior
DOI:10.1016/j.bmc.2020.115565
日期:2020.8
Rhodium-catalyzed [2 + 2 + 2] cycloadditions, sulfonyl phthalideannulations and nitroalkene reactions have been employed for the synthesis of 56 quinone-based compounds. These were evaluated against Trypanosoma cruzi, the parasite that causes Chagas disease. The reactions described here are part of a program that aims to utilize modern, versatile and efficient synthetic methods for the one or two
Stereospecific and Stereoselective Rhodium(I)-Catalyzed Intramolecular [2+2+2] Cycloaddition of Allene-Ene-Ynes: Construction of Bicyclo[4.1.0]heptenes
Treatment of the allene‐ene‐yne substrates with [RhCl(CO)2}2] effected the intramolecular [2+2+2]‐type ring‐closing reaction to produce various of tri‐ and tetracyclic derivatives containing a cyclopropane ring. The reaction is highly stereoselective as well as stereospecific with good to excellent yields.
Upon exposure to a catalytic amount of [RhCl(CO)2]2 in 1,4‐dioxane, homopropargylallene‐alkynes underwent a novel cycloisomerization accompanied by the migration of the alkyne moiety of the homopropargyl functional group to produce six/five/five tricyclic compounds in good yields. A plausible mechanism was proposed on the basis of an experiment with 13C‐labeled substrate. The resulting tricyclic derivatives
Rhodium(I)-Catalyzed Ring-Closing Reaction of Allene-Alkene-Alkynes: One-Step Construction of Tricyclo[6.4.0.0<sup>2,6</sup>
] and Bicyclo[6.3.0] Skeletons from Linear Carbon Chains
afforded bicyclo[6.3.0]undecatriene derivatives instead of tricyclic compounds, the latter of which are well known as a basic skeleton of naturally occurring octanoids. On the basis of two experiments with deuterated substrates, a plausible reaction mechanism for the construction of these products was proposed.
Mechanistic Investigation of Rh<sup>I</sup>–Catalyzed Cycloisomerization of Benzylallene-Internal Alkynes via C–H Activation
作者:Yasuaki Kawaguchi、Shigeo Yasuda、Chisato Mukai
DOI:10.1021/acs.joc.7b01048
日期:2017.7.21
effected a cycloisomerizationvia a Csp2–H bond activation to produce the tricyclo[9.4.0.03,8]pentadecapentaene skeleton. The reaction mechanism viaformation of the rhodabicyclo[4.3.0] intermediates and σ-bond metathesis between the Csp2–H bond on the benzene ring and the Csp2–RhIII bond was proposed. In addition, a plausible alternative mechanism for the previously reported cycloisomerization of the