Unsaturated organoboron compounds are important reagents in organic synthesis e.g. (pinacolato)allylboron [allyl-B(pin)] are involved in many stereoselective additions while (pinacolato)vinylboron [alkenyl-B(pin)] reagents are used in various catalytic cross coupling reactions. The stereochemical outcome of the transformations strongly rely on whether a Z- or an E-organoboron is employed, therefore there is much interest in facile and efficient access to stereodefined acyclic allyl-B(pin) and alkenyl-B(pin) compounds. Contrary to the E isomers protocols for selective synthesis of Z-allyl- or Z-alkenylboron species are uncommon, and catalytic transformations are particularly rare.
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Synthesis of Z-(Pinacolato)allylboron and Z-(Pinacolato)alkenylboron Compounds through Stereoselective Catalytic Cross-Metathesis
(Kiesewetter et al. J. Am. Chem. Soc. 2013, 135, 6026−6029)