Access to indole- and pyrrole-fused diketopiperazines via tandem Ugi-4CR/intramolecular cyclization and its regioselective ring-opening by intermolecular transamidation.
An efficient approach for the synthesis of indole- and pyrrole-fused diketopiperazines has been developed. This protocol involves the Ugi four-component reaction (U-4CR) followed by an intramolecular cyclization of the Ugi products at room temperature to afford the desired products in good to excellent yields. In addition, it is interesting to report the subsequent regioselective ring-opening of diketopiperazine unit occurring via an intermolecular transamidation reaction under mild condition, resulting in the formation of highly functionalized indole-2-carboxamides and pyrrole-2-carboxamides.
Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow, 226 001, India.
Shashi
S
Pandey
Shahnawaz
S
Khan
Awantika
A
Singh
Harsh M
HM
Gauniyal
Brijesh
B
Kumar
Prem M S
PM
Chauhan
D003500:Cyclization; D054659:Diketopiperazines / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
D054659:Diketopiperazines; D007211:Indoles; D011758:Pyrroles; C030374:indole