Indium(0)‐Mediated C–S/O Cross‐Coupling Approach Towards the Regioselective Alkylation of α‐Enolic Esters/Dithioesters: A Mechanistic Insight

Abstract

We have reported an indium(0)‐mediated C sp 3–S/O cross‐coupling approach that leads to the highly regioselective alkylation of α‐enolic acetate/dithioacetate systems. This hetero cross‐coupling reaction does not require additional co‐catalyst or promoter, and the in situ generated organoindium species promotes the reaction by acting as the coupling partner of the α‐enolic acetate/dithioacetate substrates. The excellent selectivity for C‐, S‐, or O‐alkylation is solely dependent on the nucleophilic behavior of α‐enolic acetate/dithioacetate systems. These results were further supported by DFT calculations of the relative electronic energies of the substrates and products as well as the activation barriers of the respective transformations.

β‐Ketodithioesters as Versatile Building Blocks for the Diversity Oriented Synthesis of Thioamides, α‐Allylated‐Thioesters and Ketoamides

“…[a] Entry Solvent Catalyst T allylated product 4 a with 80% yieldjust by stirring the reaction mixture for 1 h.Possible products of O-and S-alkylations with allyl bromide wasruled out under this condition as confirmed by the highly regioselective formation of 4 a.We also examined various reaction conditions by changing the ratio of reactants, EtOH as solvent and without solvent but none of the reactions could afford the product 4 a in good yield.However, in this case, we observed thatpiperidine was found acting as a base only and could not substitute the methanethiol group. Similar products were also found in literature [18] using indium metal as mediator with 12 h reaction duration in DMF.…”

“…Similar products were also found in literature using indium metal as mediator with 12 h reaction duration in DMF. The synthesized compounds were confirmed by spectroscopic methods and elemental analysis and were found to be in good agreement to those reported in the literature …”

“…The synthesized compounds were confirmed by spectroscopic methods and elemental analysis and were found to be in good agreement to those reported in the literature. [18] The functionalized ketoamides are also recognized as versatile building blocks in organic synthesis. [15] Intrigued by these reports, we thought of exploring the possibilities of converting the β-KDEs 1 to some functionalized ketoamides.Instead of piperidine, we have used many cyclic and acyclic secondary amines in the above reaction protocol to check whether any ketoamides have been formed or not.…”

Half-sandwich titanium complexes with β-oxodithioester ligands

“…2). During the preparation of this manuscript, the crystal structure of 3 was published [24], however, as our data have a better quality and the original study does not contain details about the OeH$$$S hydrogen bond, we decided to include the structure determination of 3.…”

Site‐Specific S‐Allylation of α‐Enolic Dithioesters with Morita‐Baylis‐Hillman Acetates at Room Temperature: Precursor for Thiopyrans

“…Ila and co‐workers performed the α‐C‐allylation of dithioesters with allyl bromide via conventional base‐catalyzed nucleophilic substitution. Our group reported the regioselective α‐C‐allylation of dithioesters with allyl halides via a cross‐coupling approach involving an organoindium species . Also, β‐allyl‐β‐hydroxydithioesters have been prepared by the reaction of α‐enolic dithioesters with allyl magnesium bromide .…”