(Z)-tamoxifen and tetrasubstituted alkenes and dienes via a regio- and stereospecific three-component magnesium carbometalation palladium(0) cross-coupling strategy.

[reaction: see text] The synthesis of various tetrasubstituted alkenes and dienes in a regio- and stereocontrolled manner is described. This three-component coupling strategy involves the addition of Grignard reagents to propargyl alcohols followed by palladium(0)-mediated cross-coupling with aryl or vinyl halides. This protocol has been applied to the synthesis of (Z)-Tamoxifen and related mimics.