Silver(Ⅰ)-promoted C5-H Phosphonation Of 8-aminoquinoline Amides With H-phosphonates

A simple and efficient protocol for silver(Ⅰ)-promoted phosphonation of 8-aminoquinoline amides with dialkyl H-phosphonates has been developed.The reaction proceeded smoothly under an oxidative system of Ag2CO3/K2S2O8 without any other external metal catalyst(Scheme 1).The reaction showed good functional group tolerance,and benzamides bearing electron-withdrawing,electron-donating,or electron-neutral group on the benzene ring could afford C5 phosphonated 8-aminoquinoline derivatives as target products in moderate yields.The remarkable featutes of this reaction include mild conditions,simple and environment-friendly reaction system,good functional group compatibility and high regioselectivity.The addition of radical scavenger such as 2,2,6,6-tetramethyl-1-piperidinyloxy(TEMPO)or 2,6-Di-tert-butyl-4-methylphenol(BHT)inhibited the generation of the desired product,indicating that the reaction might involve a radical process(Scheme 2).(?)...