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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

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