synthesis and catalytic functionalization of biologically active indoles

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1 Palladium-catalyzed Coupling Reactions of Indoles 57 Table 9. Palladium-catalyzed N-arylation of indole. Entry Ar-Br R 1 R 2 NH Product Yield [%] Cond. 1 [a] 2 [b] 3 [a] 4 [a] 5 [b] 6 [a] 7 [a] Br Br Br SO 2CH 3 Br SO 2CH 3 N Br N Br N Br N H N H F F N H N H N H N H N H NH 2 NH 2 Br Br H 2N H 2N N SO 2CH 3 N SO 2CH 3 N N N N N N N N 87 2 h, 120 °C 90 2 h, 120 °C 48 2 h, 120 °C 86 2 h, 120 °C 88 2 h,120 °C 0 24 h,130 °C 30 6 h,150 °C
1 Palladium-catalyzed Coupling Reactions of Indoles 58 Table 9. Palladium-catalyzed N-arylation of indole, continued. Entry Ar-Br R 1 R 2 NH Product Yield [%] Cond. 8 [a] 9 [c] Br Br N H N H F F NH 2 NH 2 Br Br H 2N H 2N N N 65 24 h,150 °C 0 24 h,180 °C Reaction conditions: [a] Pd[P(o-tolyl)3]2Cl2, (+)-BINAP, Cs2CO3. [b] Pd[P(o-tolyl)3]2Cl2, PPh3, Cs2CO3. [c] (+)-BINAP, Cs2CO3, without catalyst. In contrast the reaction was completely unsuccessful at 130 °C after more than 24 h (Table 9, entry 6). The displacement of 3-fluoroaniline instead of 5-bromoindole is not clear. Aryl fluorides have long been considered inert to palladium-catalyzed coupling reactions. [131] Only aryl fluorides with strong electron-withdrawing substituents give coupling reactions. [132] Just the high temperature can explain this behavior. The attempts to couple these substrates without catalyst failed (Table 9, entry 9). The pyridinylation of indole was also conducted in the same manner as described above. In the reaction with 3-bromopyridine and indole the coupling product resulted in a low yield (Table 9, entry 3). Nevertheless 2-bromopyridine gave under the same conditions an excellent yield (Table 9, entry 4). In general, this coupling reaction was found to be temperature dependent, higher temperature increases the yield. By raising the temperature to 180 °C, the ratio of side products was increased. However, this method allowed the synthesis of N-(3-aminophenyl)- 5-bromoindole. Grossman et al. described a new protocol for palladium-catalyzed Buchwald- Hartwig amination of aryl chlorides and -bromides with benzophenone imine as ammonia surrogate. [133] Their suggested reaction conditions are mild and were applied to numerous sensitive starting materials. Following Scheme 47 illustrates one indole-containing example.
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Leibniz-Institut für Katalyse e. V
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Für meine Eltern Siegfried und Ker
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Mein besonderer Dank gilt Dr. Anneg
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Table of Contents Preface .........
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List of Abbreviations Ac Acetyl aq
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Preface The search for drugs is an
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1 Palladium-catalyzed Coupling Reac
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1 Palladium-catalyzed Coupling Reac
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3 Publications 108 3.5 Synthesis of
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Scheme 2 Ti-catalyzed synthesis of
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mixture was used for the synthesis
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7.11 (ddd, 1H, J = 8.0 Hz, J = 7.0
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FULL PAPER DOI: 10.1002/ejoc.200800
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Synthesis of Potential 5-HT 6 Recep
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FULL PAPER DOI: 10.1002/ejoc.200700
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Synthesis of Indole-2,3-dicarboxyla
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3 Publications 132 3.8 Selective Re
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8 7 N R N R OH CO2Et CO2Et OH indol
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mixture was stirred at 78 C for 3 m
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3.89 (s, 2H, H-10), 4.27 (s, 2H, H-
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DOI: 10.1002/cssc.200700160 General
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Zn-Catalyzed Hydroamination of Term
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Zn-Catalyzed Hydroamination of Term
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3 Publications 146 3.10 Zn-Catalyze
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Over the past years, we investigate
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3 Publications 150 3.11 First Synth
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4608 K. Alex et al. / Tetrahedron L
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Publikationen 1 Titanium-Catalyzed
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synthesis and catalytic functionalization of biologically active indoles

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