RhIII‐catalyzedC−H functionalization reaction yielding isoindolinones from arylhydroxamates and ortho‐substituted styrenes is reported. The reaction proceeds smoothly under mild conditions at room temperature, and tolerates a range of functional groups. Experimental and computational investigations support that the high regioselectivity observed for these substrates results from the presence of an
Dihydrobiphenylenes through Ruthenium-Catalyzed [2+2+2] Cycloadditions of<i>ortho</i>-Alkenylarylacetylenes with Alkynes
作者:Silvia García-Rubín、Carlos González-Rodríguez、Cristina García-Yebra、Jesús A. Varela、Miguel A. Esteruelas、Carlos Saá
DOI:10.1002/anie.201309496
日期:2014.2.10
A new synthetic route to dihydrobiphenylenes has been developed. The process involves a mild RuII‐catalyzed [2+2+2] dimerization of ortho‐alkenylarylacetylenes or its more versatile variant, the Ru‐catalyzed [2+2+2] cycloaddition of ortho‐ethynylstyrenes with alkynes. Mechanistic aspects of this [2+2+2] cycloaddition are discussed.
An efficient catalytic asymmetric [2+2] cycloadditionreaction of allenyl imide and alkenes was achieved by utilizing chiral N,N′-dioxide-magnesium(II) complex as the catalyst. This protocol provided a series of axially chiral cyclobutenes in high yields with excellent enantioselectivities. A stepwise mechanism was proposed based on experimental studies and DFT calculations and π–π stacking interaction
Mechanistic Studies of Copper(I)-Catalyzed 1,3-Halogen Migration
作者:Ryan Van Hoveln、Brandi M. Hudson、Henry B. Wedler、Desiree M. Bates、Gabriel Le Gros、Dean J. Tantillo、Jennifer M. Schomaker
DOI:10.1021/ja511236d
日期:2015.4.29
An ongoing challenge in modern catalysis is to identify and understand new modes of reactivity promoted by earth-abundant and inexpensive first-row transition metals. Herein, we report a mechanistic study of an unusual copper(I)-catalyzed 1,3-migration of 2-bromostyrenes that reincorporates the bromine activating group into the final product with concomitant borylation of the aryl halide bond. A combination of experimental and computational studies indicated this reaction does not involve any oxidation state changes at copper; rather, migration occurs through a series of formal sigmatropic shifts. Insight provided from these studies will be used to expand the utility of aryl copper species in synthesis and develop new ligands for enantioselective copper-catalyzed halogenation.