Heteropolyacids as new catalysts of the Ritter reaction

Some nitriles reacted with camphene in the presence of heteropolyacids (H3PW12O40, H4SiW12O40, H7PMo12O40) as catalyst to give N-(1,7,7-trimethylbicyclo[2.2.1]hept-2-yl)-substituted amides in fairly high yields.