Friedel crafts reactions with alkenes Stereoselective synthesis of 1 1diarylalkanes

Abstract

Friedel-Crafts alkylation reaction, most probably, is the oldest organic reaction where first time a newlineLewis acid is utilized. Owing to high synthetic value of Friedel-Crafts alkylated products, the newlinedevelopment of newer and milder catalytic methods for Friedel-Crafts-type alkylations has been newlineprogressed rapidly over last few decades (Scheme 1). The features of these catalytic processes newlineare outstanding levels of chemo-, regio- or even stereo-selectivities. An asymmetric strategy of newlinethis racemic version gives enantioenriched arene-alkylated products. More recently, these newlinestrategies are frequently used to construct numerous natural products with complex architecture newlineand bioactive drug-like molecules. A brief overview of the Friedel-Crafts alkylations will be newlinepresented in Chapter I. newlineAn important strategy to prepare 1,1-diarylalkanes is Friedel-Crafts-type hydroarylation newlinereaction with olefins. The outmost advantage of these hydroarylation methods is hundred percent newlineatom-efficient product formations. In this Chapter II, we have developed a mild and newlineefficient iron triflate catalyzed Friedel-Crafts-type alkylation between and#945;,and#946;-unsaturated newlinecarbonyl compounds and electron rich benzenoid arene components (Scheme 2). This newlinereaction provides exclusively and#946;, and#946;-diaryl carbonyl compounds in good to excellent yields. newlineA series of control reactions including isotope labeling experiments helps to deduce a newlineplausible reaction mechanism. newlineAr1H Ar2 R newlineAr2 R newlineAr1 newlineR = COAr, CO2Me newlineFe(OTf)3 (10 mol%) newlineDCE, 85 C newline65-93% newline17 examples newline° newlineScheme 2 Iron-triflate-catalyzed Intermolecular Friedel-Crafts-type alkylations.