There are provided a novel compound having irreversible inhibitory activity against neuraminidase, a therapeutic agent and a detection agent for a disease involving neuraminidase. A compound represented by the following formula (I) and a salt thereof, a production method thereof, and an application method thereof, wherein: A.sup.1 represents an aryl group optionally having a substituent group or a heteroaryl group optionally having a substituent group; A.sup.2 represents --CX.sub.2R.sup.6 or --CHXR.sup.6 wherein X represents --F, --Cl, --Br, or --I; R.sup.1 represents a hydrogen atom or an alkyl group optionally having a substituent group; R.sup.2, R.sup.3, R.sup.4, and R.sup.5 represent each independently --OC(.dbd.O)R.sup.6, --OR.sup.6, --N(R.sup.6).sub.2, --N.sub.3, --NHC(.dbd.NH)NHR.sup.6, --NHCOR.sup.6, --OSO.sub.3R.sup.6, --OPO.sub.3(R.sup.6).sub.2, F, Cl, Br, or I; and R.sup.6 represents each independently a hydrogen atom, an alkyl group optionally having a substituent group, an aryl group optionally having a substituent group, or an optionally substituted heteroaryl group.