Science of Synthesis

Kauffman, M. C.; Walsh, P. J., Science of Synthesis: Stereoselective Synthesis, (2011) 2, 483.

Another class of reactions that generates allylic alcohols from alkynes and aldehydes is reductive coupling.[‌150‌–‌152‌] These reactions are catalyzed by late transition metal complexes, including nickel, rhodium, and iridium. Reductive couplings are proposed to proceed via coordination of the alkyne and the aldehyde to the catalyst, followed by formation of an oxametallocyclopentene intermediate (‌Scheme 30‌). Here the configurations of the products ‌63‌ are assigned by analogy. The reactions proceed with 100% cis selectivity, 9:1 to 95:5 regioselectivity, and up to 98% enantiomeric excess. In the cases shown, good regioselectivity is observed (typically >95:5) when the alkyne contains an aryl group and a bulky saturated substituent.[‌153‌] It is anticipated that such reductive coupling reactions will receive continued attention because they are atom economical.[‌154‌]

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References