Sulforhodamine phosphoramidite dyes

A labeled polynucleotide comprising a compound of formula IV:

• or a stereoisomer, tautomer, or salt thereof, wherein:
• R2 is halogen or SO2NH2;
• R3 is H or halogen;
• R4, R7, R8, and R11 when taken alone are independently H, halogen, or optionally substituted C1-C6 alkyl,
• R5, R6, R9 and R10 when taken alone are independently H or optionally substituted C1-C6 alkyl;
• R4 and R5 when taken together are an optionally substituted C2-C3 alkylene chain connecting the atoms to which R6 and R7 are attached;
• R6 and R7 when taken together are an optionally substituted C2-C3 alkylene chain connecting the atoms to which R6 and R7 are attached;
• R8 and R9 when taken together are an optionally substituted C2-C3 alkylene chain connecting the atoms to which R8 and R9 are attached;
• R10 and R11 when taken together are an optionally substituted C2-C3 alkylene chain connecting the atoms to which R10 and R11 are attached;
• R5 and R6, when taken together with the nitrogen atom to which R5 and R6 are attached, form a 5-membered or a 6-membered unsaturated ring;
• R9 and R10, when taken together with the nitrogen atom to which R9 and R10 are attached, form a 5-membered or a 6-membered unsaturated ring;
• n is an integer from 1 to 9;
• Y is:
• wherein:
• the wavy line is the point of attachment to Formula III;
• R12 and R13 are independently optionally substituted C1-C6 alkyl;
• W is H or L4-O—Z2;
• L3, L4, and L5 are independently an optionally substituted C2-C10 alkylene or optionally substituted C2-C30 heteroalkylene;
• Z is CH, N, NHC(O)N, or OC(O)N;
• Z1 is a nucleotide or oligonucleotide;
• and
• Z2 is a nucleotide, oligonucleotide, or H.

A compound represented by Formula VI:

• or a stereoisomer, tautomer, or salt thereof, wherein:
• R1 is L1-X;
• R2, R3, R4, and R5 are independently H, halogen, C1-C6 alkyl, or SO2NH2;
• R6 and R9 are independently H or optionally substituted C1-C6 alkyl;
• R7, R8, R10, R11, R14, and R15 are independently H or optionally substituted C1-C6 alkyl;
• L1 is an optionally substituted C2-C10 alkylene or optionally substituted C2-C20 heteroalkylene;
• X is —O—P(OCH2CH2CN)NR12R13 or:
• wherein
• L3 and L4 are independently an optionally substituted C2-C10 alkylene or optionally substituted C2-C30 heteroalkylene;
• Q is a hydroxyl protecting group;
• Z is CH, N, NHC(O)N, or OC(O)N;
• and
• R12 and R13 are independently optionally substituted C1-C6 alkyl.