Synthesis of Pyridopyrrolopyrimidines. Total Synthesis of Varioline B and Deoxyvariolin B

Significance

Reported is the synthesis of pyridopyrrolopyrimidines via the cyclization of 2-bromomethyl azaindoles with TosMIC. Attempts to further elaborate intermediate A into the variolins, however, were unsuccessful. The problem was solved by the use of tosylmethylimines (B and D). Screens of reaction conditions allowed the synthesis of F, which could ultimately be transformed into the variolin natural products.