The transition state models in two mechanistically distinct pathways, involving (i) an enamine carboxylic acid (path-A, 4) and (ii) an enamine carboxylate (path-B, 8), in the proline-catalyzed asymmetric α-amination have been examined using DFT methods. The path-A predicts the correct product stereochemistry under base-free conditions while path-B accounts for reversal of configuration in the p...

We report a study involving the successful merger of two separate chiral catalytic cycles: a chiral anion phase-transfer catalysis cycle to activate Selectfluor and an enamine activation cycle, using a protected amino acid as organocatalyst. We have demonstrated the viability of this approach with the direct asymmetric fluorination of α-substituted cyclohexanones to generate quaternary fluorine...

Eleven N-enamine derivatives of daunorubicin and of its 5-imino analogue as well as of doxorubicin have been synthesized and evaluated for antileukemic activity in vitro and in vivo. Comparison of biological activities of examined compounds with other enamine derivatives of daunorubicin, reported earlier by us, has indicated that the optimal activity is shown by N-(1-carboethoxypropen-1-yl-2)da...

In the title compound, C(12)H(12)N(2)O(4), the dihedral angle between the pyridine and enamine planes is 3.5 (3)°, while the angle between the dioxanedione (seven atoms) and enamine planes is 4.6 (3)°. The dioxane ring approximates an envelope conformation.

D-Amino acid oxidase catalyzes the nonoxidative conversion of oc-amino-P-chlorobutyrate to or-ketobutyrate, but does not catalyze its oxidation to P-chloroketobutyrate. The elimination reaction requires the oxidized flavoprotein, i.e. it does not occur with the apoenzyme or when the enzymebound flavin is reduced. The occurrence of this elimination reaction supports the proposal that removal of ...

We herein report the synthesis of 3-fluoro-2-methylene-pyrrolidine (3a) and -piperidine (3b) from 1,5- and 1,6-aminoalkynes, respectively, using a combination of a gold-catalyzed hydroamination reaction followed by electrophilic trapping of an intermediate cyclic enamine by Selectfluor. Careful attention was paid to the elucidation of the mechanism and Selectfluor was suggested to play the doub...

RidA (for Reactive Intermediate Deaminase A) proteins are ubiquitous, yet their function in eukaryotes is unclear. It is known that deleting Salmonella enterica ridA causes Ser sensitivity and that S. enterica RidA and its homologs from other organisms hydrolyze the enamine/imine intermediates that Thr dehydratase forms from Ser or Thr. In S. enterica, the Ser-derived enamine/imine inactivates ...