Synthesis of 5,5′-dihydroxyleucine and 4-fluoro 5,5′-dihydroxyleucine, the reduction products of 4-carboxyglutamic and 4-carboxy-4-fluoroglutamic acids

Copper-Catalyzed 1,1-Alkylmonofluoroalkylation of Terminal Alkynes with Diazo Compounds and 2-Fluoro-1,3-dicarbonyl Compounds: Access toward (E)-β-Monofluoroalkyl-β,γ-unsaturated Esters or Ketones

An efficient copper-catalyzed three-component 1,1-alkylmonofluoroalkylation of terminal alkynes, diazo compounds, and 2-fluoro-1,3-dicarbonyl compounds for the synthesis of (E)-β-monofluoroalkyl-β,γ-unsaturated esters or ketones has been developed. The methodology features a broad substrate scope, an inexpensive and easily available catalytic system, and excellent selectivity with good yields. The mechanism of the tandem Cu-catalyzed cross-coupling and nucleophilic addition of allenes has been investigated.

Ligand-free copper-catalyzed regio- and stereoselective 1,1-alkylmonofluoroalkylation of terminal alkynes

A novel copper-catalyzed highly regio- and stereoselective 1,1-alkylmonofluoroalkylation of terminal alkynes without an external ligand has been developed.

The Nucleophilicity of Persistent α-Monofluoromethide Anions

α-Fluorocarbanions are key intermediates in nucleophilic fluoroalkylation reactions. Although frequently discussed, the origin of the fluorine effect on the reactivity of α-fluorinated CH acids has remained largely unexplored. We have now investigated the kinetics of a series of reactions of α-substituted carbanions with reference electrophiles to elucidate the effects of α-F, α-Cl, and α-OMe substituents on the nucleophilic reactivities of carbanions.

Synthesis and SAR studies of indole-based MK2 inhibitors

Chemistry has been developed to specifically functionalize two structurally similar classes of indole-based MK2 inhibitors at positions prompted by a combination of X-ray crystallographic and computer assisted drug design. A gain in molecular potency was obtained by introducing aminomethyl groups to the lactam rings of 6-arylcarbamoyl-tetrahydro-beta-carbolinone and 6-arylcarbamoyl-dihydropyrazino[1,2-a]indolone MK2 inhibitors. In addition, improvements in molecular potency were achieved by expansion of the lactam from a 6- to 7-membered ring leading to 7-arylcarbamoyl-tetrahydro-[1,4]diazepino[1,2-a]indolones.

Inhibition of transcellular tumor cell migration and metastasis by novel carba-derivatives of cyclic phosphatidic acid

Cyclic phosphatidic acid (1-acyl-sn-glycerol-2,3-cyclic phosphate; cPA) is a naturally occurring analog of lysophosphatidic acid (LPA) with a variety of distinctly different biological activities from those of LPA. In contrast to LPA, a potent inducer of tumor cell invasion, palmitoyl-cPA inhibits FBS- and LPA-induced transcellular migration and metastasis. To prevent the conversion of cPA to LPA we synthesized cPA derivatives by stabilizing the cyclic phosphate ring; to prevent the cleavage of the fatty acid we generated alkyl ether analogs of cPA. Both sets of compounds were tested for inhibitory activity on transcellular tumor cell migration. Carba derivatives, in which the phosphate oxygen was replaced with a methylene group at either the sn-2 or the sn-3 position, showed much more potent inhibitory effects on MM1 tumor cell transcellular migration and the pulmonary metastasis of B16-F0 melanoma than the natural pal-cPA. The antimetastatic effect of carba-cPA was accompanied by the inhibition of RhoA activation and was not due to inhibition of the activation of LPA receptors.

Synthesis of 1,2-dithiolane analogues of leucine for potential use in peptide chemistry

[reaction: see text]1,2-Dithiolanes present several points of interest for both peptide and medicinal chemistry, yet no chiral alpha-amino acids containing this five-membered heterocyclic system are available. We report here the first synthesis of N- and C-protected derivative of (S)-2-amino-3-(1,2-dithiolan-4-yl)propionic acid (Adp) and its 1,3-dithiolic form.