DIETHOXYMETHYL - A USEFUL NITROGEN-PROTECTING GROUP FOR LACTAMS AND AMIDES

Treatment of the lactams 3a-e and the amide 3f with triethyl orthoform ate leads to the N-diethoxymethyl substituted derivatives 4a-f. Additi onally, the indolinones 3a and 3b can react at the lactam alpha-positi on to give the reaction products 2 and 5, respectively. The diethoxyme thyl group can be easily removed by subsequent treatment with trifluor oacetic acid and NaOH.