A synthetic route to chiral C(3)-functionalized phthalides via a Ag(I)-catalyzed allylation/transesterification sequence

A Ag(I)-catalyzed synthesis of chiral C(3)-substituted phthalides (8a-f) via a Sakurai-Hosomi allylation/transesterification reaction is described (ee ≤86%). A notable feature of this reaction is that it utilizes ortho-substituted aldehydes, which are a class of compounds that generally afford poor levels of stereoinduction when applying most known catalytic asymmetric allylation approaches. It was also found that elongation of the n-alkyl chain length (R1, up to n=6; R2=H) of the starting alkyl 2-formylbenzoates (7g-i) improved the enantiomeric excess (ee) of the product.

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