The present invention relates to sydnone compounds substituted in position 4, to a process for the preparation of a first compound of interest C1 functionalized with a sydnone compound of the invention and to the corresponding functionalized C1 compound of interest. The present invention also relates to a process for the preparation of a conjugate of two compounds of interest C1 and C2 implying a sydnone compound according to the invention, and to the obtained conjugate. The present invention also relates to a process for preparing a compound of interest C2 comprising a strained alkyne moiety functionalized with a sydnone according to the invention and to the corresponding functionalized compound of interest C2.
