Regiospecific C-acylation of pyrroles and indoles using N-acylbenzotriazoles
Alan R Katritzky1, Kazuyuki Suzuki, Sandeep K Singh
1Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA. katritzky@chem.ufl.edu
Abstract:
Reactions of pyrrole (2) or 1-methylpyrrole (4) with readily available N-acylbenzotriazoles 1a-g (RCOBt, where R = 4-tolyl, 4-nitrophenyl, 4-diethylaminophenyl, 2-furyl, 2-pyridyl, 2-indolyl, or 2-pyrrolyl) in the presence of TiCl(4) produced 2-acylpyrroles 3a-g and 5a-g in good to excellent yields. 1-Triisopropylsilylpyrrole (6) under the same conditions gave the respective 3-acylpyrroles 7a-g. Similarly, indole (9) and 1-methylindole (11) gave the corresponding 3-acylated derivatives 10a-g and 12a-g. These results demonstrate that N-acylbenzotriazoles such as 1c,f,g are mild, regioselective, and regiospecific C-acylating agents of particular utility when the corresponding acid chlorides are not readily available.
Related Concept Videos
Amines to Amides: Acylation of Amines
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary amide...
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Nucleophilic Aromatic Substitution: Elimination–Addition
Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Regioselectivity of Electrophilic Additions-Peroxide Effect


![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)