6070-59-3Relevant articles and documents
Total synthesis of micromide: A marine natural product
Han, Jianrong,Lian, Jingtang,Tian, Xia,Zhou, Shengwei,Zhen, Xiaoli,Liu, Shouxin
, p. 7232 - 7238 (2015/02/19)
This paper describes an efficient procedure for the synthesis of micromide, a natural product that shows anti-solid-tumor activity. Our strategy involved the synthesis of N-nosyl-protected amino acids and their N-methylation with iodo-methane. The hindered oligopeptides containing N-methyl amino acids were synthesized in excellent yields and high purities.[ampi]]
Catalytic asymmetric amination of N-nonsubstituted α-alkoxycarbonyl amides: Concise enantioselective synthesis of mycestericina F and G
Berhal, Farouk,Takechi, Sho,Kumagai, Naoya,Shibasaki, Masakatsu
supporting information; experimental part, p. 1915 - 1921 (2011/03/22)
In an attempt to explore the synthetic utility of a ternary asymmetric catalyst comprising La(NO3)3·6H2O, amide-based ligand (R)-L1, and D-valine tert-butyl ester H-D-Val-OtBu, 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 mycestericina F (3a) and G (3b).
Managing highly coordinative substrates in asymmetric catalysis: A catalytic asymmetric amination with a lanthanum-based ternary catalyst
Mashiko, Tomoyuki,Kumagai, Naoya,Shibasaki, Masakatsu
supporting information; experimental part, p. 14990 - 14999 (2010/01/30)
Full details of a catalytic asymmetric amination with a lanthanum/amide-based ligand catalyst system are described. A catalyst comprising La(NO3)3·6H2O, (R)-3a and H-D-Val-OtBu was identified to promote the catalytic asymmetric amination of nonprotected succinimide derivative 1 with as little as 1 mol % catalyst loading. Mechanistic studies by various spectroscopic analyses and several control and kinetic experiments suggested that the catalyst components were in equilibrium between the associated and dissociated forms, and that the reaction likely proceeded through a La(NO3)3· 6H2O/(R)-3a/H-D-Val-OtBu ternary complex. This catalyst system was also effective for asymmetric amination of N-nonsubstituted α-alkoxycarbonyl amides 7, hitherto unprecedented substrates in asymmetric catalysis, probably due to their attenuated reactivity and difficult stereocontrol, affording the amination products in up to >99% yield and >99% ee. The high catalytic performance and enantiocontrol of the reaction with highly coordinative substrates were achieved by the activation/recognition of the substrates exerted by coordination to lanthanum and hydrogen bonding cooperatively in the transition state.
