Allylboronates by Olefin Metathesis

In contrast to the preparative methods described above, a functionalized allyl-boronate can be created from a simpler allylboronate by olefin cross-metathesis [81, 82]. Here, treatment of pinacol allylboronate (2) with various olefin partners, exemplified with styrene in Equation (33), in the presence of ruthenium catalyst 58 smoothly furnishes a more elaborate 3-substituted allylboronate, the cross product 38 [81]. These reactions are noteworthy for their exceptional functional group tolerance allylboronates bearing primary halides can be directly synthesized using this method. Unfortunately, the E/Z selectivity in the formation of the 3-substituted allylboronates is variable. This metathesis approach to allylboronates was employed as the beginning of a tandem cross-metathesis/carbonyl allylation process [82] (discussed in more detail in Section 6.4.1.3). 

Using the same concept, Hoveyda and co-workers recently employed molybdenum derived chiral complexes to develop a net catalytic enantioselective, cross metathesis process based on either the kinetic resolution of racemic allylic alcohols or the asym- 

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