The present invention provides a compound represented by the following chemical formula (I); a tautomer or stereoisomer of the compound; or a salt of the compound, the tautomer, or the stereoisomer. In the chemical formula (I), R1 and R2 are each a Group 1 element or a protecting group of an amino group and may be identical to or different from each other, or alternatively, R1 and R2 together may form a protecting group of an amino group. R3 is a Group 1 element or a protecting group of a hydroxy group. R4 is a Group 1 element or —PR5R6R7R8 (R5, R6, R7, and R8 are each a Group 1 element, a lone electron pair, a Group 16 element, a Group 17 element, or a protecting group of a phosphorus atom, and may be identical to or different from each other). J is a hydrogen atom or an arbitrary atomic group, A is a hydrogen atom, a hydroxy group, an alkyl group, an aralkyl group, an alkoxy group, an electron-withdrawing group, a silylene group, or a sulfide group, or alternatively, J and A together may form a linker. L is a single bond or a linker (a linking atom or a linking atomic group), the main chain length (the number of main chain atoms) of the linker is arbitrary, L may or may not contain each of C, N, O, S, P, and Si in the main chain, and may or may not contain each of a single bond, a double bond, a triple bond, an amide bond, an ester bond, a disulfide bond, an imino group, an ether bond, a thioether bond, and a thioester bond in the main chain. Z is an atomic group that can form a peptide bond with a labeling compound, or is an atom or atomic group including a label.