Catalytic Transformations of Benzylic Carboxylates and Carbonates

Abstract

Benzylic carboxylates and carbonates react with various molecules in the presence of homogeneous palladium or cobalt catalysts. The catalytic transformations occur at the benzylic carbons of the substrates, affording benzylic substitution products. This review surveys the catalytic reactions using benzylic carboxylates and carbonates as substrates. Furthermore, the related studies on (h 3benzyl)metal complexes are summarized in order to facilitate the understanding and consideration of the catalytic substitution. 1 Introduction 2 Chemistry of the (h 3-Benzyl)metal Complex 2.1 Structure of the (h 3-Benzyl)metal Complex 2.2 Reactivity of the (h 3-Benzyl)metal Complex 3 Catalytic Transformations of Benzylic Esters 3.

Mechanistic Studies for Synthesis of Bis(indolyl)methanes: Pd-Catalyzed C–H Activation of Indole–Carboxylic Acids with Benzyl Alcohols in Water

“…The powerfulness of these complexes is still far from other well-established Tsuji-Trost reactions, merely due to a more recent development [1][2][3][4][5][6][7][8][9]. Palladium-catalyzed benzylations with benzylic alcohols via the (η 3 -benzyl)palladium intermediate are especially challenging, because the reactivity of benzylic alcohols towards Pd(0) is poor compared to benzylic halides, esters, carbonates and phosphates.…”

Palladium-catalyzed substitution of (coumarinyl)methyl acetates with C-, N-, and S-nucleophiles

“…In the forthcoming sections, the coupling of this coumarin template to arylboronic acids [56–61], amines [47] and arylsulfinates is described [62]. Moreover, compared to related methods for palladium-catalyzed benzylic substitution that require specialized ligands [45,47,60–62], we report that coumarin π-benzyl formation is easily achieved with simple PPh 3 ligated palladium.…”

“…Substitution of methylcoumarins to form compounds akin to 2 typically utilizes the corresponding halomethylcoumarin and highly stabilized nucleophiles or amines [6–15]. Due to the sensitivity and toxicity of related benzyl halides, there has been interest in catalytically activating hydroxymethylarene and heteroarenes (e.g., benzyl alcohol derivatives) toward reactions with nucleophiles [45–55]. In this realm, we [53,55] and others [54] have focused efforts on catalyzing benzylic substitutions with less-stabilized (DMSO p K a ~ 20–30) nucleophiles through decarboxylative coupling.…”

Transition Metal-Catalyzed Decarboxylative Allylation and Benzylation Reactions

“…Since that time, the breadth of nucleophilic coupling partners has steadily increased and this work has been recently reviewed. 157 For example, malonate-type nucleophiles, 158 boronic acids, 159 and more recently, direct arylation methods, 160 have been utilized to make new benzyl C–C bonds though palladium-benzyl intermediates. With respect to heteroatomic nucleophiles, catalytic benzylations of phenols, 161 amines, 158d and sulfonyl nucleophiles 162 have all been disclosed.…”

“…157b Conversely, decarboxylative benzylations are still in their infancy; decarboxylative benzylations of phenols, 161 diphenylglycinate imines, 164 acetylides, 165 and ketones 165 have only recently been reported.…”