5-(3-Amino-1-propyn-1-yl)-2'-deoxyuridine 5'-(Tetrahydrogen Triphosphate) is an intermediate in the synthesis of Texas Red-5-dUTP (T320100), a fluorescence-labelled nucleotide analog. Texas Red-5-dUTP is used diagnostically for detection of rearranged SS18 in formalin-fixed, paraffin-embedded synovial sarcoma.