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Table 3 Synthesis of chromans 3a
intermediate in the formation of tricyclic indole product 2 from
the amidoarylation of 1 under these conditions.
In summary, we have developed a Rh(III)-catalyzed intra-
molecular amidoarylation and hydroarylation for the switch-
able syntheses of 3,4-fused tricyclic indoles and chromans from
alkyne tethered acetanilides via aryl C–H bond activation. In
this process, two distinct types of complex molecules from the
identical starting materials are achieved simply by a slight
change of reaction conditions. The reaction features atom-
and step-economy, high product yields and a practical proce-
dure. Studies on the synthetic applications of this protocol are
being carried out in our laboratory.
Financial support for this research provided by the NNSFC
(21172030 and 21272034), the Young Scientific Research Foun-
dation of Jilin Province (20140520083JH) and the Fundamental
Research Funds for the Central Universities (12QNJJ010) is
greatly acknowledged.
Notes and references
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a
Reactions conducted on a 0.2 mmol scale. Condition C: (Cp*RhCl2)2
(2.5 mol%), AgSbF6 (10 mol%), PivOH (5.0 equiv.), t-AmOH (0.1 M),
120 1C. PivOH (1.0 equiv.), yields of the corresponding tricyclic
indoles 2 are in parentheses. Condition A, yields of tricyclic indoles
b
c
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Scheme 1 Proposed mechanism for the formation of 2 and 3.
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protonated by the pivalic acid to give the corresponding alkene
derivative 3 with regeneration of the catalyst. In addition, the
hydroarylation product 3g was treated with the amidoarylation
conditions (Tables 1 and 2, condition A) for 10 h, the corres-
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7308 | Chem. Commun., 2014, 50, 7306--7309
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