ORGANIC
LETTERS
XXXX
Vol. XX, No. XX
000–000
Nucleopalladation Triggering the
Oxidative Heck Reaction: A General
Strategy to Diverse β‑Indole Ketones
Qian Wang,† Liangbin Huang,† Xia Wu, and Huanfeng Jiang*
School of Chemistry and Chemical Engineering, South China University of Technology,
Guangzhou 510640, P. R. China
Received September 24, 2013
ABSTRACT
A simple and efficient palladium-catalyzed oxidative coupling between 2-alkynyl anilines and allylic alcohols is described by using cheap and green
dioxygen as the oxidant. These cross-couplings have a large functional group tolerance and are of higher reactivity toward electron nonbaised allylic
alcohols. The resultant β-indole ketones are readily converted to pharmaceutically significant β-indole alcohol/amine and pyrrolo[2,1-a]isoquinolines.
In recent decades, the alkyne-directed transformations
catalyzed by palladium have become a powerful tool
to construct highly functionalized products.1 In this re-
gard, nucleopalladation of CÀC triple bonds arguably
represents one of the most attractive strategies to form
multiple carbonÀcarbon and carbonÀheteroatom bonds,
thus leading to various significant organic molecules in one
step.2À5 Generally, different kinds of nucleophiles includ-
ing halides,2 acetates,3 amines,4 and electron-rich carbon
nucleophiles5 have attacked alkynes activated by PdII to
afford the vinyl-Pd species, which could be captured by CO
and olefins.3,6,7 However, olefins used to capture the vinyl-Pd
species have usually been the electron-biased olefins, such as
R,β-unsaturated olefins and styrenes [eq 1].3,7 This has been
due to electron nonbiased olefins having sluggish reactivity
and facing the dilemma of selective β-H elimination.8,9
Lei and Kommu respectively reported the Pd-catalyzed
oxidative coupling between benzoboric acid and allyic
† These authors contributed equally.
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r
10.1021/ol4027683
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