cyanoethyl 4-(2-cyanoethylseleno)-5'-dimethoxytrityl-2',3'-dideoxythymidin-3'-yl N,N-diisopropylaminophosphoramidite
cyanoethyl 4-(2-cyanoethylseleno)-5'-dimethoxytrityl-2',3'-dideoxythymidin-3'-yl n,n-diisopropylaminophosphoramidite