Asymmetric Synthesis of β-Substituted α-Methylenebutyro- lactones via TRIP-Catalyzed Allylation : Mechanistic Studies and Application to the Synthesis of (S)-(−)-Hydroxymatairesinol

Asymmetric allylation of (hetero)aromatic aldehydes by a zinc(II)-allylbutyrolactone species catalyzed by a chiral BINOL-type phosphoric acid gave β-substituted α-methylenebutyrolactones in 68 to >99% ee and 52–91% isolated yield. DFT studies on the intermediate Zn2+-complex – crucial for chiral induction – suggest a six-membered ring intermediate, which allows the phosphoric acid moiety to activate the aldehyde. The methodology was applied to the synthesis of the antitumour natural product (S)-(−)-hydroxymatairesinol. SNIC through Uppsala Multidisciplinary Center for Advanced Computational Science (UPPMAX). Grant Number: Project p2011197 Austrian Science Fund (FWF). Grant Number: Erwin-Schrödinger-Fellowship (J3193-N17)