Science of Synthesis

Kauffman, M. C.; Walsh, P. J., Science of Synthesis: Stereoselective Synthesis, (2011) 2, 480.

Catalysts based on metals other than zinc have been employed in the enantioselective alkenylation of aldehydes. A practical example that involves the addition of alkenyl(trimethoxy)silanes with a copper catalyst generated using bis(phosphine) ‌57‌ is illustrated in ‌Scheme 28‌.[‌145‌] The alkenylation may proceed via an alkenylcopper intermediate that reacts with the aldehyde to give allylic alcohols ‌58‌. Support for this proposal comes from the use of an alkenylboronate ester, which generates the same alkenylcopper intermediate and gives nearly identical enantioselectivities.[‌146‌] One advantage of this method is that the alkenylsilane is air stable, and the copper starting material is inexpensive.

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References