Ultralow molecular weight heparin

A heparin oligomer having a structure of Formula (I):

• or a pharmaceutically acceptable salt, solvate, hydrate, polymorph, co-crystal, tautomer, stereoisomer, isotopically labeled derivative, or prodrug thereof, wherein:
• n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10;
• R1 is —ORA, —SRA, —N(RA)2, halogen, an optionally substituted monosaccharide, or an optionally substituted oligosaccharide;
• each occurrence of RA is independently —H, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted heteroalkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to a nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom, or two occurrences of RA are joined together with their intervening atoms to form an optionally substituted heterocyclic ring or optionally substituted heteroaryl ring;
• each of R2, R4, R11, and R12 is independently —H, —OH, —OSO3H, or —SO3H;
• each of R3 and R10 is independently —SO3H, —H, optionally substituted C1-C6 alkyl, or an oxygen protecting group;
• R5 is —ORB, —SRB, —N(RB)2, halogen, an optionally substituted monosaccharide, or an optionally substituted oligosaccharide;
• each occurrence of RB is independently —H, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted heteroalkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, a nitrogen protecting group when attached to a nitrogen atom, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom, or two occurrences of RB are joined together with their intervening atoms to form an optionally substituted heterocyclic ring or optionally substituted heteroaryl ring;
• and
• each occurrence of RC is independently —H, optionally substituted C1-C6 alkyl, or an oxygen protecting group;
• provided that one of R1 and R5 is an optionally substituted monosaccharide.