amount of InCl3 and aceticanhydride remarkably promotes the Knoevenagel condensation of a variety of aldehydes and activated methylene compounds. This catalytic system accommodates aromatic aldehydes containing a variety of electron-donating and -withdrawing groups, heteroaromatic aldehydes, conjugate aldehydes, and aliphatic aldehydes. Central to successfully driving the condensation series is the formation
A novel catalyst-economic strategy with a recovered palladium catalyst was successfully applied for multi-task and maximum reuse in different types of one-by-one downstream reactions, from catalytic hydrogenation to Suzuki and Sonogashira-type cross-coupling reactions, Knoevenagel condensations, and trans-Knoevenagel-like condensations.
Enantioselective Lewis Acid Catalyzed Michael Reactions of Alkylidene Malonates. Catalysis by <i>C</i><sub>2</sub>-Symmetric Bis(oxazoline) Copper(II) Complexes in the Synthesis of Chiral, Differentiated Glutarate Esters
作者:David A. Evans、Tomislav Rovis、Marisa C. Kozlowski、C. Wade Downey、Jason S. Tedrow
DOI:10.1021/ja002246+
日期:2000.9.1
C2-symmetricbis(oxazoline)−Cu(II) complexes 1 catalyze the Mukaiyama Michael reaction of alkylidene malonates and enolsilanes. The use of hexafluoro-2-propanol is essential to induce catalyst turnover. High enantioselectivities are exhibited by bulky alkylidene malonate β-substituents using catalyst 1a. The glutarate ester products are readily decarboxylated to provide chiral 1,5-dicarbonyl synthons
the addition to various unsaturated carbonyl compounds, while calcium triflimide [Ca(NTf2)2] efficiently catalyzed the addition to nitroolefins. Friedel–Crafts alkylation of indole and its derivatives with a variety of electron-deficient alkenes catalyzed by Mg and Ca salts has been studied. The dependence of the results on the nature of the starting olefins, substituents on indole, and Michael acceptors
CO Versus CC Bond Cleavage: Selectivity Control in Lewis Acid Catalyzed Chemodivergent Cycloadditions of Aryl Oxiranyldicarboxylates with Aldehydes, and Theoretical Rationalizations of Reaction Pathways
A clean break: Lewisacidcatalyzedchemodivergent [3+2] cycloadditions of aryloxiranyldicarboxylates with aldehydes are revealed, in which the CC or CObondcleavage of oxiranes can be controlled by the use of Ni(ClO4)2 or Sn(OTf)2 catalysts (see scheme). Possible reactionpathways for these transformations are demonstrated by theoretical calculations.