synthesis and catalytic functionalization of biologically active indoles
synthesis and catalytic functionalization of biologically active indoles
synthesis and catalytic functionalization of biologically active indoles
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1 Palladium-catalyzed Coupling Reactions <strong>of</strong> Indoles 61<br />
Br<br />
OTBDMS<br />
Pd(OAc) 2 (1 mol%)<br />
lig<strong>and</strong> I (2 mol%)<br />
LiHMDS (1.3 equiv)<br />
N<br />
Me R<br />
toluene, 100 °C, 24 h<br />
Me<br />
1R2 1 2 R RN<br />
OTBDMS<br />
NH<br />
N<br />
Me<br />
190 191a-j<br />
Me<br />
N P<br />
H<br />
N<br />
OTBDMS<br />
H<br />
N<br />
OTBDMS H<br />
N<br />
Me<br />
Me<br />
N<br />
N<br />
191a (85%)<br />
Me<br />
Me<br />
191b (40%)<br />
191c<br />
N<br />
lig<strong>and</strong> I<br />
H<br />
N<br />
OTBDMS<br />
Me<br />
H<br />
N<br />
191d (60%)<br />
N<br />
Me<br />
F<br />
191e (91%)<br />
Me<br />
N<br />
Me<br />
OTBDMS<br />
N<br />
Me<br />
Me<br />
(85%)<br />
OTBDMS<br />
N<br />
OTBDMS<br />
N<br />
OTBDMS<br />
O<br />
N<br />
OTBDMS<br />
191f<br />
Me<br />
N<br />
Me<br />
(50%)<br />
Me<br />
N<br />
191g<br />
Me<br />
(75%)<br />
N<br />
Me<br />
Me<br />
191h (55%)<br />
N<br />
OTBDMS<br />
H<br />
N<br />
OTBDMS<br />
N<br />
Me<br />
N<br />
Me<br />
Me<br />
191i (73%) 191j (91%)<br />
Me<br />
Scheme 49. Palladium-catalyzed amination <strong>of</strong> 3-silyloxy-5-bromo-2-methylindole.<br />
Very <strong>active</strong> catalysts for Buchwald-Hartwig amination have been devised not only<br />
for aryl bromides but also for the less re<strong>active</strong> aryl chlorides or sulfonates. [138] In<br />
addition, the reaction has been extended to many NH-containing species other<br />
than amines such as amides, lactams, ureas, <strong>and</strong> hydrazines etc.. Hess <strong>and</strong><br />
Kirsch examined Buchwald-Hartwig amination <strong>of</strong> �-chloroacrolein by lactams <strong>and</strong><br />
heteroarylamines. [139] Vinyl chlorides [140] were scarcely studied <strong>and</strong> to investigate<br />
their reactivity in cross-coupling amination is an interesting application. Following<br />
Scheme 50 pictured the palladium-catalyzed Buchwald-Hartwig amination <strong>of</strong> �-<br />
chloroacrolein with indole.