Catalytic Asymmetric Amination of N‐Nonsubstituted α‐Alkoxycarbonyl Amides: Concise Enantioselective Synthesis of Mycestericin F and G

Abstract In an attempt to explore the synthetic utility of a ternary asymmetric catalyst comprising La(NO 3 ) 3 ⋅6H 2 O, amide‐based ligand ( R )‐ L1 , and D ‐valine tert ‐butyl ester H‐ D ‐Val‐O t Bu, we investigated a catalytic, asymmetric amination of functionalized N‐nonsubstituted α‐alkoxycarbonyl amides using di‐ tert ‐butyl azodicarboxylate as an electrophilic aminating reagent. A highly functionalized, cyclic N‐nonsubstituted α‐alkoxycarbonyl amide delivered the desired amination product in up to 96 % enantiometric excess, with the requisite functionalities of the polar heads of sphingosines with the appropriate stereochemical arrangement. The rapid asymmetric assembly of these functional groups allowed a concise enantioselective synthetic route to sphingosines to be established with a broad flexibility towards derivative synthesis. These studies have culminated in an efficient catalytic enantioselective total synthesis of immunosuppressive fungal metabolites mycestericin F ( 3 a ) and G ( 3 b ).