The Fluorenone Imines of Glycine Esters and Their Phosphonic Acid Analogues

Abstract

Viel reaktiver als die entsprechenden Benzophenon‐Imine, die häufig für die Synthese von α‐Aminosäuren verwendet wurden, sind die Titelverbindungen: Sie gehen Mannich‐Reaktionen mit Iminen in Gegenwart katalytischer Mengen einer Base ein, wobei α,β‐Diaminosäure‐ und α,β‐Diaminophosphonsäure‐Derivate mit hoher syn‐Diastereoselektivität entstehen (siehe Schema). Auch eine asymmetrische Variante der Reaktion wird beschrieben. Boc=tert‐Butoxycarbonyl.

Mimicking Nature to Make Unnatural Amino Acids and Chiral Diamines

“…[30] Desymmetrization of meso anhydrides [36] and kinetic resolution of azalactones [37] were first reported by Seebach using a chiral Ti IV complex as a catalyst. Phase transfer catalysts have been developed by O'Donnell, [38] Corey, [39] Maruoka (12) [40] and others [41] for stereoselective alkylation of imino esters (Scheme 6d). Various ketones and aldehydes have been used, including benzophenone and p-chlorobenzaldehyde to form the imino esters.…”

Asymmetric Synthesis of α,β‐Diaminophosphonic Acid Derivatives with a Catalytic Enantioselective Mannich Reaction

“…[10] Although these particular phosphonic acids bear considerable interest, being a,b-diamino acid analogues, [11] and their activity as efficient aminopeptidase inhibitors has been already demonstrated, [12] their enantioselective synthesis has not been thoroughly studied. To the best of our knowledge, only a handful of examples based on chiral auxiliary methodologies, [13] and a single catalytic asymmetric reaction, limited to a-methyl-a,b-diaminophosphonates, [14] have been reported so far.…”

Guanidine Organocatalyst for the Asymmetric Mannich‐Type Reaction between α‐Isothiocyanato Imide and Sulfonyl Imines

“…[3] Most of these approaches have focused on Mannich reactions of glycine imines or nitro esters with various imines, which provide a direct and favorable method for the construction of these compounds. [4][5][6] In recent years, a-isothiocyanato imides have been employed as glycine imine equivalents in Mannich reactions. Willis and co-workers reported the first example of a Mannich reaction of the a-isothiocyanato imide with imines using chiral magnesium complex derivatives from DBFox.…”