A route to RNA with an alkylating group at the 5'-triphosphate residue.

Reaction of ATP with N,N,N'-tris(2-chloroethyl), N' (p-formyl-phenyl)propylenediamine-1,3 (abbreviation C13R) afforded a gamma-ester of ATP (abbreviation C1RpppA) - the product of alkylation by an aliphatic nitrogen mustard residue of C13R. The alkylating activity of the aromatic nitrogen mustard residue of C1RpppA is suppressed by the electron-acceptor effect of the p-formyl group. C1RpppA is a substrate of RNA-polymerase, and affords RNA with C1RpppA-residues at the 5'-termini.