cycloaddition of cyclopropane with π-unsaturated compound has emerged as a
powerful tool for the construction of cyclic structural units during the past
decades. However, their cycloaddition reaction still remains an elusive
challenge. Different from highly strained cyclopropanes bearing fused π-unsaturation,
lessstrained cyclopropanes bearing adjacent π-unsaturation prove quite inert in
transition metal-catalyzed cloaddition reactions.
Prof. Ye’s group reported a Ni-Al bimetallic synergism to facilitate the
cycloaddition reaction of cyclopropyl carboxamide with alkyne for the first
time, in which the ligand-Ni-Al combination probably played a triple role: activating
cyclopropane substrate, directing nickel oxidative addition and stabilizing the
in situ formed nickellacycle. In addition, a successful enantioselective
control of this reaction was also achieved by the use of taddol-derived chiral
phosphine oxide ligand with up to 94% ee.
demonstrate the applicability of the amide group, further transformation of
products was conducted. When subjected to acidic conditions, cyclopentene was
easily transformed into the corresponding acid, a versatile synthetic
intermediate, in 85% yield but with partial racemization. Cyclopentene was
treated by oxidation conditions to deliver a dearylated amide in 81% yield.
summary, this work has demonstrated the first example of nickelcatalyzed
enantioselective cycloaddition reaction of unreactive cyclopropyl carboxamide
with alkyne. A series of synthetically useful cyclopentenyl carboxamides are
obtained in up to 99% yield and 94% ee. The cooperation of ligand with Ni and
Al may provide new insights into the C-C bond activation of unreactive
research was published in the Journal of
the American Chemical Society. The first author is PhD. Qi-Sheng Liu and
the joint first author is PhD. De-Yin Wang.
detailed information on this work, please click here: