A novel microgel-supported acylating reagent (MGAR) was prepared by combining ring-opening metathesis polymerization (ROMP) and Activators Re-Generated by Electron Transfer for Atom Transfer Radical Polymerization (ARGET ATRP): (1) synthesis of an ATRP macroinitiator 3 by living ROMP of oxanorbornene-based activated ester 1, derived from N-hydroxysuccinimide, using the Grubbs initiator RuCl(2)(PCy(3))(2)(=CHPh) and (Z)-but-2-ene-1,4-diyl bis(2-bromopropanoate) (BDBP) as a terminating agent; (2) synthesis of MGAR 4 by ARGET ATRP of styrene (S) and divinylbenzene (DVB) using the prepared macroinitiator 3, a CuCl(2)/Me(6)TREN (tris[2-(dimethylamino)ethyl]amine) catalyst system, a Sn(Oct)(2) [tin(II)2-ethylhexanoate] reducing agent. The synthesized microgels 4 exhibit excellent acyl (acetyl, benzoyl, phenylsulfonyl) transfer properties for primary and secondary amines (n-BuNH(2), Et(2)NH, morpholine, etc.) under mild conditions (25 degrees C, 13.5-14 h) affording N-acylamines with high yield (95.6-100%) and purity (94.1-96.0%).