Syntheses and antimicrobial activities of 3-acyltetramic acid derivatives.

Silver‐Catalyzed Cross‐Coupling of Isocyanides and Active Methylene Compounds by a Radical Process

“…[21] Herein we provide an extremely simple way to access such kind of valuable compounds. [22] Al arge-scale (10 mmol) synthesis was carried out under the silver-catalyzed conditions.P leasingly,t he reaction of 1a and 2i proceeded smoothly,even with ar educed the catalyst loading (10 mol %), albeit affording product 3i with aslightly decreased yield. Thehighly functionalized alkenes generated by this protocol offer opportunities for further synthetic manipulation to access functionalized heterocyclic motifs.For instance,s ynthetic conversion of N-aryl-b-enaminamide (3i) into the functionalized pyrazole 6 and isoxazole 7 were attained in good yields by reacting with hydrazine hydrate and hydroxylamine hydrochloride,respectively.…”

A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids

“…At first we prepared three nitrogen-protected 3-acyltetramic acids ( 7 – 9 ) according to the Matsuo [ 7 ] variant of Lacey–Dieckmann [ 8 ] condensation ( Scheme 1 ) [ 9 – 10 ]. Reaction of either β-ketoester 4 or Meldrum’s acid derivative 9 with suitably protected glycine esters ( 5 , 6 , 10 ), followed by base-induced condensation furnished the desired tetramic acid model compounds as crystalline solids after treatment with a small quantity of methanol.…”

Silver‐Catalyzed Cross‐Coupling of Isocyanides and Active Methylene Compounds by a Radical Process

“…All the products were obtained with an E configuration, and the stereochemistry was confirmed with the help of an NOE experiment involving 3ak.It is worth mentioning that synthetic methods for enamines like 3,w hich having two different EWGs,are rare. [22] Al arge-scale (10 mmol) synthesis was carried out under the silver-catalyzed conditions.P leasingly,t he reaction of 1a and 2i proceeded smoothly,even with ar educed the catalyst loading (10 mol %), albeit affording product 3i with aslightly decreased yield. Gratifyingly,a nu nprecedented C sp3 ÀHcarbamoylation of b-ketoesters with tert-butyl isocyanide (4a)w as discovered, and led to ar ange of tricarbonylmethanes (5a-h)i nm oderate to high yields.…”