Addition of nitrogen dioxide to carbon-carbon double bond followed by a cyclization to construct nitromethylated isoquinolinediones.

Heterocyclic derivatives 4-(nitromethyl)isoquinoline-1,3(2H,4H)-diones were synthesized via a tandem nitration/cyclization reaction of N-alkyl-N-methacryloyl benzamides under metal-free conditions. The cheap and available reagent nitrogen dioxide was used as the nitro source, as well as the oxidant. For the substrates with various substituent groups, the reaction proceeded smoothly to give the corresponding isoquinolinedione derivatives in moderate to good yields. The products could be converted into aminomethyl or hydroxyl substituted heterocyclic derivatives by the simple reduction.