Solid-phase rhodium carbenoid N-H insertion reactions: the synthesis of a diverse array of indoles.
A solid-phase synthesis of an array of indoles is reported. The key step in our approach involves a N-H insertion reaction of N-alkylanilines into a highly reactive polymer-bound rhodium carbenoid intermediate to yield the corresponding alpha-arylamino-beta-ketoester. These insertion products were then treated under acid-catalyzed cyclodehydration conditions to yield a series of polymer-bound indole esters, which were subsequently cleaved from the resin under Lewis acid-promoted amidation conditions to yield the desired indoles in good yields and with excellent purities.
Lee
Sang-Hyeup
SH
The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Clapham
Bruce
B
Koch
Guido
G
Zimmermann
Jürg
J
Janda
Kim D
KD
D002384:Catalysis; D003500:Cyclization; D007202:Indicators and Reagents; D007211:Indoles / Q000138:chemical synthesis*; D012117:Resins, Synthetic; D012238:Rhodium / Q000737:chemistry*
D007202:Indicators and Reagents; D007211:Indoles; D012117:Resins, Synthetic; D012238:Rhodium