Manganese complex-catalysed α-alkylation of ketones with secondary alcohols enables the synthesis of β-branched carbonyl compounds

Abstract

Diverse β-functionalised carbonyl compounds were synthesized via a manganese(i) complex-catalysed α-alkylation of ketones with secondary alcohols.

A Proton‐Responsive Pyridyl(benzamide)‐Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols

“…The deuterium experiments are consistent with a 1,4-addition of H 2 to chalcone and indicate the involvement of both the metal and the participating ligand in the transfer-hydrogenation pathways (Scheme 6). [107] The results obtained with 1 are similar to those reported using Mn [137] and Fe [110] bifunctional catalysts. In contrast, a Co-catalyzed alkylation of acetophenone with secondary alcohol led to a comparable deuterium incorporation at both αand β-positions owing to either reversible steps or a deuterium/hydrogen scrambling on the Co complex.…”

“…A comparison of the performances of reported protonresponsive catalysts was made (see, Scheme S2). It is apparent that 1 exhibits better catalytic efficacy in terms of lower base loading and higher TON and TOF values for both α-alkylation of ketones [38,110,121,[135][136][137][138] and β-alkylation of secondary alcohols. [87,94,104,106,139]…”

Borrowing Hydrogen for Organic Synthesis

“…130 Scheme 12 shows the reaction conditions for the borrowing hydrogen procedure and the subsequent retro-Friedel−Crafts reaction, with representative examples. 128 In recent years, this approach with secondary alcohols has been extended to cobalt, 131 iron, 132 manganese, 133 and transition-metal-free catalysis. 134 Scheme 10.…”

Ruthenium-Catalyzed α-Alkylation of Ketones Using Secondary Alcohols to β-Disubstituted Ketones

“…(iii) Unsubstituted or other aryl ketones are less successful and, thus, suffer from a limited substrate scope. Importantly, the Ph* group averts ketone self-condensation reactions, which can also be detached to prepare a range of carbonyl derivatives such as esters and amides through a retro-Friedel–Crafts acylation reaction. − To circumvent these drawbacks, an efficient catalytic system is essential for the success of this process and its broad application, which also should preclude the self-condensation of the nonsubstituted ketone substrates. Recently, selective cross-coupling of secondary alcohols to β-disubstituted ketones was reported by our group .…”

“…In 2017, the Donohoe group reported the synthesis of β-branched ketones via α-alkylation of ketones using secondary alcohols . Very recently Co, Fe, and Mn-catalyzed α-alkylation of ketones using secondary alcohols was developed (Scheme b). All of these enticing developments can be summarized as follows: (i) Stoichiometric excess base is required, which results in aldol side reactions.…”