By
using tandem Ru-catalysis, internal alkynes can be coupled with
aldehydes for the synthesis of β,γ-unsaturated ketones.
The catalyst promotes alkyne transformations with high regioselectivity,
with examples that include the differentiation of a methyl vs ethyl
substituent on the alkyne. Mechanistic studies suggest that the regioselectivity
results from a selective allene formation that is governed by allylic
strain
