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 51<br />
2- <strong>and</strong> 3-bromo-N-methyl<strong>indoles</strong> catalyzed by P(tert-Bu)3 <strong>and</strong> Pd(dba)2. To<br />
prevent competition between the reacting amine <strong>and</strong> indole N-H, N-methyl<strong>indoles</strong><br />
were used instead <strong>of</strong> the parent <strong>indoles</strong>. The reactions <strong>of</strong> 2- <strong>and</strong> 3-bromo-Nmethyl<strong>indoles</strong><br />
with N-methylaniline (Table 8, entries 1 <strong>and</strong> 3) occurred at room<br />
temperature whereas reactions <strong>of</strong> 2- <strong>and</strong> 3-bromo-N-methyl<strong>indoles</strong> with<br />
diphenylamine (Table 8, entries 2 <strong>and</strong> 4) occurred at 100 °C. Non reaction <strong>of</strong> these<br />
bromo<strong>indoles</strong> were observed with primary or secondary alkylamines <strong>and</strong> with<br />
primary arylamines.<br />
Further palladium-catalyzed aminations were listed in this publication <strong>and</strong><br />
proceeded with a range <strong>of</strong> electron-rich heteroaromatic bromides <strong>and</strong> chlorides<br />
with certain classes <strong>of</strong> amines.<br />
Table 8. Amination <strong>of</strong> indole bromides with Pd(dba)2/PtBu3.<br />
Ar-Br HNRR´<br />
Pd(dba) 2/PtBu 3<br />
NaOtBu<br />
toluene<br />
Ar-NRR´<br />
Entry Ar-Br Amine Product Cond. Yield [%]<br />
1 N<br />
Me<br />
Br<br />
2 N<br />
Me<br />
Br<br />
3<br />
4<br />
Br<br />
N<br />
Me<br />
Br<br />
N<br />
Me<br />
HNMePh N<br />
Me<br />
NMePh<br />
rt, 16 h 83<br />
HNPh2 N<br />
Me<br />
NPh2 HNMePh<br />
HNPh2<br />
NMePh<br />
N<br />
Me<br />
NPh 2<br />
N<br />
Me<br />
100 °C, 16 h 86<br />
rt, 16 h 70<br />
100 °C, 16 h 71