Synthesis of 2-methyl-5-amino-4-oxo-3-sulfonyl esters as precursors of pseudodipeptides

Summary The synthesis of 2-methyl-5-amino-4-oxo-3-sulfonyl esters, potential precursors of XaaΨ[COCH₂]Ala, XaaΨ[E-CH=CH]Ala and XaaΨ[CH₂CH₂]Ala pseudodipeptides, has been investigated by alkylation of aminoacid-derived β-ketosulfones with ethyl 2-bromo- or 2-triflyloxypropionate in different basic conditions. Yields in 2-methyl-5-amino-4-oxo-3-sulfonyl esters are low but starting β-ketosulfones are recovered in good yield.     

Inhibition of P-glycoprotein-mediated multidrug efflux by aminomethylene and ketomethylene analogs of reversins

Several aminomethylene analogs and a ketomethylene analog of reversins were synthesized in order to evaluate their ability to inhibit P-glycoprotein-mediated drug efflux in K562/R7 human leukemic cells overexpressing P-glycoprotein. These analogs retained good activity compared to cyclosporin A and the original reversins.     

An efficient synthesis of anhydrides of 2-monosubstituted succinic acid monoesters and their application to the Dakin–West reaction: Isolation of some 5-succinyloxyoxazole intermediates

A rapid and versatile synthesis of 2-monosubstituted monosuccinates and their bimolecular anhydrides is described. The reaction of these anhydrides with N-Fmoc-protected dipeptides under the modified Dakin–West reaction affords mainly the corresponding 5-succinyloxyoxazoles.     

An efficient synthesis of anhydrides of 2-monosubstituted succinic acid monoesters and their application to the Dakin–West reaction: Isolation of some 5-succinyloxyoxazole intermediates

Summary A rapid and versatile synthesis of 2-monosubstituted monosuccinates and their bimolecular anhydrides is described. The reaction of these anhydrides withN-Fmoc-protected dipeptides under the modified Dakin-West reaction affords mainly the corresponding 5-succinyloxyoxazoles.     

Synthesis of 2-methyl-5-amino-4-oxo-3-sulfonyl esters as precursors of pseudodipeptides

The synthesis of 2-methyl-5-amino-4-oxo-3-sulfonyl esters, potentialprecursors of Xaa[COCH₂]Ala, Xaa[E-CH=CH]Ala andXaa[CH₂CH₂]Ala pseudodipeptides, has been investigated byalkylation of aminoacid-derived -ketosulfones with ethyl 2-bromo- or2-triflyloxypropionate in different basic conditions. Yields in 2-methyl-5-amino-4-oxo-3-sulfonyl esters are low but starting -ketosulfones are recovered in good yield.