Zinc-Mediated Asymmetric Allylation of Chiral N-tert-Butanesulfinyl Aldimines with 3-Bromomethyl-5H-furan-2-one

Abstract

The zinc-mediated asymmetric allylation of chiral Ntert-butanesulfinyl aldimines with 3-bromomethyl-5H-furan-2-one proceeded in good anti/syn selectivities, providing optically pure substituted α-methylene-γ-butyrolactones bearing chiral amine with moderate to excellent yields (28-92%) and diastereoselectivities (76% to >99% de).

From α-Bromomethylbutenolide to Fused Tri(Tetra) Cyclic Dihydrofurandiones through Barbier Reaction–Heck Arylation Sequence

“…If such reactions are well described [3,4,5,6,7], the use of ortho -substituted benzaldehydes and further ortho -bromide derivatives remain scarcely reported [14]. In our case, 2 smoothly reacted with the starting butenolide at room temperature in THF for 16 h, in the presence of activated zinc powder (1.1 eq.)…”

“…The presence of a sterically demanding naphthalene platform, as well as a bromine atom, did not affect the stereoselectivity observed for other aromatic substrates [3,4,5,6,7]. The combined presence of the lactone carbonyl and the benzyl alcohol induces the formation of hydrogen bonds associating three molecules in the solid state.…”

“…Our first attempts were based on a Pd(II) catalytic system reported in the literature for an analogous transformation [3,4,5,6,7]. Pd(PPh 3 ) 2 Cl 2 (5 %) in combination with K 2 CO 3 (2 eq.)…”

“…The conjugated exo -vinylidene fragment is believed to be essential to a wide array of biological activities and thus drove the development of numerous preparation methods [3,4,5,6,7]. The interest of the scientific community for such lactones also stems from their use as intermediates in the synthesis of complex and polycyclic molecular architectures.…”