Superacid Promoted Synthesis of 9,9'-Spirobifluorenes and Related Aza- and Diazaspirocycles
Jacob C Hood1, Douglas A Klumpp1
1Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States.
Abstract:
A variety of 9,9'-spirobifluorenes and related azaspirocycles and diazaspirocycles have been prepared in high yields by intramolecular Friedel-Crafts reaction using the Brønsted superacid, triflic acid (CF3SO3H). Compared to weaker Brønsted acids, the superacid consistently provides better yields along with reduced reaction times and it eliminates the need for heating. The superacid is particularly effective when dicationic electrophilic intermediates are generated in the conversions, for example with the diazaspirocycle syntheses.
Related Concept Videos
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Cycloaddition Reactions: Overview
Acid-Catalyzed Ring-Opening of Epoxides
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
