One‐Pot Sequential Catalytic Hydration of Alkynes and α‐Alkylation with Alcohols for the Synthesis of α‐Alkylated Ketones

Abstract

The present research will also facilitate the development of one-pot, sequential, catalytic reactions based on "hydrogen autotransfer" (or "hydrogen-borrowing") processes.

Advances in One-Pot Synthesis through Borrowing Hydrogen Catalysis

“…Basically, α-alkylation of ketones (14) could be integrated together with the hydration reaction of alkynes within the context of BH methodology as depicted in Scheme 6. 74 In this case, in the presence of (iPr)AuCl (15), silver triflate (AgOTf), and water, a series of alkynes (11) were first hydrated to give the corresponding methyl ketones (12), which in turn were α-alkylated by adding the iridium complex [Cp*IrCl 2 ] 2 (16), KOtBu, and alcohols to the reaction mixture. 74 This reaction is highly attractive due to the availability of starting materials, the undeniable atom efficiency, the good to outstanding yields, and the low consumption of chemicals and energy.…”

Brønsted Acid‐Mediated Hydrative Arylation of Unactivated Alkynes

“…[16,17] Examples include the gold-and mercurycatalyzed addition of sulfoxideso rN-oxides to alkynes as well as iridium catalysis. [18,19] Herein we describe the synthesis of a-arylatedk etones by an atom-economical, Brønsted acid-catalyzed hydrative arylation of alkynes using sulfoxides. Inspired by our prior work on ynamides, [20a] we speculated that the protonation of unactivated alkynes 1a-l could transiently furnish highly reactive vinyl cations I (Scheme 1).…”

C−C Bond Formation of Benzyl Alcohols and Alkynes Using a Catalytic Amount of KOtBu: Unusual Regioselectivity through a Radical Mechanism

“…Also,t he reaction proceeding by the Markovnikov addition of water to the alkyne would result in aproduct in which the C = Og roup is located on the side of the alkyne derivative,aspreviously reported. [7] However,inthis case,as confirmed by X-ray diffraction, the product contains the C = O group on the side of the alcohol (see Figure S11).…”

“…CÀCb ond-forming reactions of alkynes with alcohols in the presence of at ransition-metal catalyst and water (or without water) to form a-alkylated ketones have been reported (Scheme 1c). [7] Ther eactions proceed by Markovnikov hydration of the alkyne to form am ethyl ketone, followed by C-alkylation of the methyl ketone with the alcohol. Theobtained product contains the C=Ogroup on the side derived from the alkyne.Herein, we present aCÀCbond- forming reaction of benzyl alcohols with alkynes using acatalytic amount KO t Bu (Scheme 1d).…”