Corrin Syntheses. Part III1: Synthesis of Corrin Complexes via A→B Ring Closure. Preparation of A/D Components. Issue 11 (December 2015)

• Record Type: Journal Article
• Authors: Pesaro, Mario; Elsinger, Fritz; Boos, Helmut; Felner‐Cabogy, Ivo; Gribi, Hanspeter; Wick, Alexander; Gschwend, Heinz; Eschenmoser, Albert
• Is Part Of: Helvetica chimica acta. Volume 98:Issue 11/12(2015:Nov.)
• Page Start: 1683
• Page End: 1754
• Publication Date: 2015-12
• Subjects: Vitamin B12 -- Corrins -- Ring‐closure reactions; Chemistry -- Periodicals; Chemistry, Analytical -- periodicals; Chimie -- Périodiques; 540
• DOI: 10.1002/hlca.201200308
• Languages: English
• ISSNs: 0018-019X

Abstract

Abstract: Since our work on corrin synthesis was intended to be a model study for the construction of the ligand system of vitamin B12 ( cf. Part I of this series), the choice of an A / D component that would contain an angular Me group at the junction between rings A and D seemed crucial. Such a Me group was expected to direct (through its steric impact) a regioselective functionalization of the two carbonyl groups of a corresponding dilactam structure that appeared to be the obvious type of intermediate in the construction of an A / D component. The target A / D structure envisaged originally was the methyl ester derivative1a ( cf. Fig. 1 ). However, observations in an early phase of our work made it clear that we better aim at the nitrile derivative1b, instead of the corresponding methyl ester. Nitrile1b was in fact synthesized, but not used as A / D component, because, on the way to its synthesis, the opportunity emerged to prepare structure2 . As A / D component, 2 differs from1b by the isomeric positioning of the angular Me group, it could be prepared regio‐ as well as stereoselectively and, therefore, much more efficiently than1b .