The Bradsher cycloaddition reaction, also known as the Bradsher cyclization reaction is a form of the Diels-Alder Reaction which involves the [4+2] addition of a common dienophile with a cationic aromatic azadiene such as acridizinium or isoquinolinium.
The Bradsher cycloaddition was first reported by C. K. Bradsher and T. W. G. Solomons in 1958.
References
Bradsher cycloaddition Wikipedia(Text) CC BY-SA