Chelatbildende Carbonsäureamide als stabile Relay‐Schutzgruppen für Carbonsäuren und ihre Spaltung unter milden Bedingungen

Abstract

In der modernen organischen Synthese ist der Einsatz von Schutzgruppen meist unumgänglich. [1,2]

Unusual Orthogonality in the Cleavage Process of Closely Related Chelating Protecting Groups for Carboxylic Acids by Using Different Metal Ions

“…[3] Although the related amides 11 and 12 feature only pyridine and a tertiary-amino function as potentially vulnerable entities, we demonstrated their chemical stability under various reaction conditions. For bpa-protected carboxylic acids, such as amide 10, we have previously demonstrated chemical robustness under a variety of reaction conditions.…”

“…[3] This strategy was demonstrated by using carboxamides of bis(picolyl)amine (bpa), for example, carboxamide 1, and allowed removal of the protecting group under mild conditions to produce either the methyl ester or the carboxylic acid (Scheme 1). [3] This strategy was demonstrated by using carboxamides of bis(picolyl)amine (bpa), for example, carboxamide 1, and allowed removal of the protecting group under mild conditions to produce either the methyl ester or the carboxylic acid (Scheme 1).…”

“…These results confirm the importance of the identity of the counter ion. The synthesis of the relevant bis-(picolyl)ethylenediamine-derived amine (bped), 9, started with reductive amination by using N-Boc-ethylenediamine (Boc = tert-butoxycarbonyl), pyridine-2-carboxaldehyde, and NaBH-(OAc) 3 as the reducing reagent. These amides are closely related to 4, but contain an additional pyridine moiety as an extra coordination entity.…”

Unusual metal complexes of N,N-bis(2-picolyl)amides – A comparative study of structure and reactivity

“…[15][16][17][18][19][20][21] In addition, the cleavage can proceed in an intramolecular fashion and give γ-, δ-and ε-lactones in moderate to high yields. [22] Figure 1: Parameters for the quantitative description of the (non-)/planarity of amides; a) twist angle τ, b) Winkler-Dunitzparameter χ N .…”

Modulation of Olefin Metathesis Reactions by Chelation

“…The obtained values with the different salts are a reflection of the stability of the chelation as already observed in earlier studies concerning methanolysis of chelating amides with different metal salts. [8][9][10] These data also revealed that the bpa unit forms more-stable complexes with copper salts. Hence, we surmised that there would be a stronger activation when the complexes with CuCl, CuCl 2 , or Cu(OTf) 2 were applied.…”