better substrates than ortho-gem-dibromovinylanilines, although the reason was
not so clear. Through a cascade intramolecular aryl amination and intermolecular
Heck reaction, 2-vinylic indoles 11 could be obtained with good yields [29].
Additionally, 2-alkynyl indoles 12 could be assembled via a cascade aryl
amination/Sonogashira reaction process [30].
Based on the same strategy, Lautens et al. developed a method for synthesizing indole embodied polycyclic heteroaromatics 14, in which a silver-promoted
domino Pd-catalyzed intramolecular amination and C–H activation arylation were
involved (Scheme 4) [31].
Recently, Alper et al. added Pd-catalyzed carbonylation to the above domino
process and developed a concise route for the synthesis of 2-carboxyindoles 16
from ortho-gem-dibromovinylanilines 15 (Scheme 5) [32].
Using 2-(2-haloalkenyl)aryl halides 17 as coupling partners, the Willis group
discovered an alternative route to indoles (Scheme 6) [33, 34]. Thus, Pd-catalyzed
double amination of 17 with aniline delivered 1-phenyl indoles 18 in good yields.
Scheme 3 Synthesis of 2-aryl indoles, 2-vinylic indoles and 2-alkynyl indoles via Pd-catalyzed
intramolecular N-arylation
Scheme 2 Synthesis of 2,3-disubstituted indoles via Pd-catalyzed cascade intermolecular C–N
bond formation and intramolecular Heck reaction
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Y. Jiang and D. Ma
not so clear. Through a cascade intramolecular aryl amination and intermolecular
Heck reaction, 2-vinylic indoles 11 could be obtained with good yields [29].
Additionally, 2-alkynyl indoles 12 could be assembled via a cascade aryl
amination/Sonogashira reaction process [30].
Based on the same strategy, Lautens et al. developed a method for synthesizing indole embodied polycyclic heteroaromatics 14, in which a silver-promoted
domino Pd-catalyzed intramolecular amination and C–H activation arylation were
involved (Scheme 4) [31].
Recently, Alper et al. added Pd-catalyzed carbonylation to the above domino
process and developed a concise route for the synthesis of 2-carboxyindoles 16
from ortho-gem-dibromovinylanilines 15 (Scheme 5) [32].
Using 2-(2-haloalkenyl)aryl halides 17 as coupling partners, the Willis group
discovered an alternative route to indoles (Scheme 6) [33, 34]. Thus, Pd-catalyzed
double amination of 17 with aniline delivered 1-phenyl indoles 18 in good yields.
Scheme 3 Synthesis of 2-aryl indoles, 2-vinylic indoles and 2-alkynyl indoles via Pd-catalyzed
intramolecular N-arylation
Scheme 2 Synthesis of 2,3-disubstituted indoles via Pd-catalyzed cascade intermolecular C–N
bond formation and intramolecular Heck reaction
90
Y. Jiang and D. Ma