Boron Lewis Acid Catalyzed Intermolecular trans-Hydroarylation of Ynamides with Hydroxyarenes

Abstract

An atom-economic protocol for the efficient and highly chemo- and stereoselective trans-hydroarylation of ynamides with hydroxyarenes catalyzed by B­(C6F5)3 has been developed. Use of readily available starting materials, low catalyst loading, mild reaction conditions, a broad substrate scope, ease of scale-up, and versatile functionalizations of the enamide products make this approach very practical and attractive.

Atom-economic and stereoselective catalytic synthesis of fully substituted enol esters/carbonates of amides in acyclic systems enabled by boron Lewis acid catalysis

“… 27 In contrast to the studies on the difunctionalization reactions by using carboxylic acids, the successful use of esters as the bifunctional reagents 28 in difunctionalization of unsaturated hydrocarbons to build molecular complexity still lags behind and had been limited to the intramolecular reactiosn. 29 In line with our interest in developing atom-economic reactions and main group catalysis, 30 we report here a complementary and main-group-catalyzed intermolecular 1° and 2° alkyl acyloxylations of ynamides with benzyl carboxylates or carbonates, in which the RCO 2 -C(sp 3 ) bond is formally cleaved and added across ynamides to generate the acyclic β,β-disubstituted enol esters/carbonates of amides. The synthetic utility is illustrated by the late-stage modification of natural products and drug derivatives and the construction of acyclic quaternary carbon centers by palladium-catalyzed decarboxylative allylic alkylation of fully substituted amide enolates.…”

Catalytic intermolecular hydrofunctionalizations of ynamides

“…More recently, the group of Feng developed an intriguing anti -hydroarylation of ynamides with phenols with a catalytic amount of B(C 6 F 5 ) 3 (Scheme 19). 46 The protocol features mild reaction conditions, a broad substrate scope and moderate to good anti -selectivity. Phenols are initially activated by B(C 6 F 5 ) 3 via coordination with the oxygen atom.…”

Three-component Friedel–Crafts-type difunctionalization of ynamides with (hetero)arenes and iodine(iii) electrophile

“…10 Despite these remarkable achievements employing functionalized aryl donors, the intermolecular arylative difunctionalization of ynamides using readily available unfunctionalized arenes and heteroarenes, paralleling the aforementioned iodoarylation, has remained elusive. 11,12…”