Reductive Bis-addition of Aromatic Aldehydes to α,β-Unsaturated Esters via the Use of Sm/Cu(I) in Air: A Route to the Construction of Furofuran Lignans

Abstract

The novel bis-addition of benzaldehydes to acrylates or maleates was achieved by the direct use of samarium metal with the assistance of CuI under mild conditions under dry air, and the useful 2-hydroxylalkyl-γ-butyrolactons and lignan derivatives were thus constructed with high efficiency. The key factors that influence the reaction efficiency were investigated. The use of potassium iodide and molecular sieves as additives can improve the reaction efficiency remarkably.

Organic Synthesis with Elemental Lanthanides – Going Beyond Samarium and Ytterbium

“…Synthesis of furofuran lignans using a Sm/CuI system. [67] new radical processes, new dehalogenation reactions, especially CÀ F bond activation, and unprecedented bimetallic chemistry involving transition metals. In certain cases, a "lanthanide effect" was observed, leading to varying reactions outcomes depending on the metal used.…”

“…The reaction worked also nicely with acrylates affording 2-hydroxylalkyl-γ-butyrolactones. [67] Very recently, the transformation of a large array of organic halides 158 (alkyl, allyl, benzyl and aryl halides) with different carbonyl compounds 159 was explored using catalytic CuI and Sm as a stoichiometric reducing agent (Scheme 36). [68,69] In THF, Grignard-like reactivity was observed leading to the formation of alcohols 160 (Scheme 36a).…”

Copper‐Catalyzed Homocoupling of Alkyl Halides in the Presence of Samarium

“…Our recent interests in the transition‐metal catalysis in organic transformations– brought our attention to the combination of samarium reagents and copper salts. By virtue of the exceptional coupling ability of copper, which was widely used in the construction of new carbon‐carbon bonds and carbon‐hetero bonds, the samarium/copper system has exhibited impressive reactivity to promote novel reactions –…”

“…On the other hand, it should be pointed out that potassium iodide probably exchanges its iodide ion with other alkyl halides thus improving the reactivity of the substrates to a certain extent. Actually potassium iodide has proved to be crucial in some organic transformations in which cuprous iodide was used as a catalyst …”

Access to Diarylmethanol Skeletons via a Samarium/Copper-Mediated Sequential Three-Component C–H Functionalization Reaction

“…Since samarium reagents possess an excellent ability of reductive coupling as well as moderate price and low toxic, it has become one of the hot topics in single-electron transfer reagents . However, although the direct use of samarium metal is more attractive for large-scale preparation while samarium diiodide shows extremely poor atom economy and high sensitivity to air and moisture in most cases, very few reactions were explored, probably due to the mild reactivity of samarium metal .…”