Synthetic studies relevant to biosynthetic research on vitamin B12. Part 5. Synthesis of (RS)-ring-B imide

Abstract

Future biosynthetic research on vitamin B₁₂ depends on the synthesis of a family of isobacteriochlorin pigments. A key building block required for this work is 2-(2-methoxycarbonylethyl)-3-methoxycarbonylmethyl-3-methylsuccinimide, usually called the ring-B imide. A practical synthesis of the racemic form of this substance is described which can yield multigramme quantities of product.