Grubbs-Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

Abstract The novel dicationic metathesis catalyst [(RuCl 2 (H 2 ITapMe 2 )(=CH-2-(2-PrO)- N-heterocyclic carbene (NHC) ligand was prepared. The reactivity was tested in ring opening metathesis polymerization (ROMP) under biphasic conditions using a nonpolar organic solvent (toluene) and the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium The structure of Ru-2 was confirmed by single crystal X-ray analysis. 163

Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts

Abstract A highly enantioselective α-amination of 3-substituted oxindoles with azodicarboxylates catalyzed by amino acids-derived chiral phosphine catalysts is reported. The corresponding products containing a tetrasubstituted carbon center attached to a nitrogen atom at the C-3 position of the oxindole were obtained in high yields and with up to 98% ee. 72

Molecular-oxygen-promoted Cu-catalyzed oxidative direct amidation of nonactivated carboxylic acids with azoles

Abstract A copper-catalyzed oxidative direct formation of amides from nonactivated carboxylic acids and azoles with dioxygen as an activating reagent is reported. The azole amides were produced in good to excellent yields with a broad substrate scope. The mechanistic studies reveal that oxygen plays an essential role in the success of the amidation reactions with copper peroxycarboxylate as the key intermediate. Transamidation occurs smoothly between azole amide and a variety of amines. 215

Stereocontrolled synthesis of 5-azaspiro[2.3]hexane derivatives as conformationally "frozen" analogues of L-glutamic acid

Abstract Several strategies aimed to "freeze" natural amino acids into more constrained analogues have been developed with the aim of enhancing in vitro potency/selectivity and, more in general, drugability properties. The case of L-glutamic acid (L-Glu, 1) is of particular importance since it is the primary excitatory neurotransmitter in the mammalian central nervous system (CNS) and plays a critical role in a wide range of disorders like schizophrenia, depression, neurodegenerative diseases such as Parkinson's and Alzheimer's and in the identification of new potent and selective ligands of ionotropic and metabotropic glutamate receptors (GluRs). To this aim, bicycle compound Ib was designed and synthesised from D-serine as novel [2.3]-spiro analogue of L-Glu. This frozen amino acid derivative was designed to further limit the rotation around the C3-C4 bond present in the azetidine derivative Ia by incorporating an appropriate spiro moiety. The cyclopropyl moiety was introduced by a diastereoselective rhodium catalyzed cyclopropanation reaction

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

Abstract 3β-Azidocholest-5-ene (3) and (3β)-3-(prop-2-yn-1-yloxy)cholest-5-ene (10) were prepared as substrates to synthesize a variety of three-motif pharmacophoric conjugates through CuAAC. Basically, these conjugates included cholesterol and 1,2,3-triazole moieties, while the third, the pharmacophore, was either a chalcone, a lipophilic residue or a carbohydrate tag. These compounds were successfully prepared in good yields and characterized by NMR, MS and IR spectroscopic techniques. Chalcone conjugate 6c showed the best antimicrobial activity, while the lactoside conjugate 27 showed the best cytotoxic effect in vitro. 192