The molecule is the intermediate in the biosynthesis of vitamin B12 from uroporphyrinogen III in which four methyl groups have been introduced at positions 2, 7, 17 and 20 of the tetrapyrrole framework, together with ring contraction of the framework forming a bond between C-1 and C-19, leaving C-20 as part of an acetyl group bonded to C-1. It is a conjugate acid of a precorrin-4(8-).
3-[(2S,3S,4Z,7S,17R)-1-acetyl-8,13,17-tris(2-carboxyethyl)-2,7,12,18-tetrakis(carboxymethyl)-2,7,17-trimethyl-10,15,21,23-tetrahydro-3H-corrin-3-yl]propanoic acid