Julie Broggi

The Isolation of [Pd{OC(O)H}(H)(NHC)(PR3)] (NHC = N-Heterocyclic Carbene) and Its Role in Alkene and Alkyne Reductions Using Formic Acid

The [Pd(SIPr)(PCy3)] complex efficiently promotes a tandem process involving dehydrogenation of formic acid and hydrogenation of C-C multiple bonds using H2 formed in situ. The isolation of a key catalytic hydridoformatopalladium species, [Pd{OC(O)H}(H)(IPr)(PCy3)], is reported. The complex plays a key role in the Pd(0)-mediated formation of hydrogen from formic acid. Mechanistic and computational studies delineate the operational role of the palladium complex in this efficient tandem sequence.

The Influence of Phosphane Ligands on the Versatility of Ruthenium–Indenylidene Complexes in Metathesis

The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy(3) with phosphanes of varying electron-donating properties could be a straightforward manner to improve catalytic activity, a methodical study dealing with the effect of phosphane fine-tuning in ruthenium-indenylidene catalysts was performed. Challenged to establish how the electronic properties of para-substituted phosphane ligands translate into catalyst activity, the versatile behaviour of these new ruthenium-indenylidene complexes was investigated for a number of metathesis reactions.

N-Heterocyclic carbene containing complexes in catalysis

In this report, recent advancements in metal-catalysed homogeneous transformations involving N-heterocyclic carbene (NHC) are described. In spite of the efficiency of NHCs in organocatalysis1 and their advantageous properties in coordination chemistry,2 and because of the ever growing interest in NHC chemistry and space limitations, the focus of this report is transition-metal mediated catalysis.

Novel Antiviral C5-Substituted Pyrimidine Acyclic Nucleoside Phosphonates Selected as Human Thymidylate Kinase Substrates

Acyclic nucleoside phosphonates (ANPs) are at the cornerstone of DNA virus and retrovirus therapies. They reach their target, the viral DNA polymerase, after two phosphorylation steps catalyzed by cellular kinases. New pyrimidine ANPs have been synthesized with unsaturated acyclic side chains (prop-2-enyl-, but-2-enyl-, pent-2-enyl-) and different substituents at the C5 position of the uracil nucleobase. Several derivatives in the but-2-enyl- series 9d and 9e, with (E) but not with (Z) configuration, were efficient substrates for human thymidine monophosphate (TMP) kinase, but not for uridine monophosphate-cytosine monophosphate (UMP-CMP) kinase, which is in contrast to cidofovir. Human TMP kinase was successfully crystallized in a complex with phosphorylated (E)-thymidine-but-2-enyl phosphonate 9e and ADP. The bis-pivaloyloxymethyl (POM) esters of (E)-9d and (E)-9e were synthesized and shown to exert activity against herpes virus in vitro (IC(50) = 3 μM) and against varicella zoster virus in vitro (IC(50) = 0.19 μM), in contrast to the corresponding inactive (Z) derivatives. Thus, their antiviral activity correlates with their ability to act as thymidylate kinase substrates.

Alkyne-Azide Click Chemistry Mediated Carbanucleosides Synthesis

Hitherto unknown 1,4-disubstituted-[1,2,3]-triazolo-4′,4′-dihydroxymethyl-3′-deoxy carbanucleosides were synthesized based on a “click approach.” Various alkynes were introduced on a key azido intermediate by the “click” 1,3-dipolar Huisgen cycloaddition. Their antiviral activities and cellular toxicities were evaluated on vaccinia virus. None of the synthesized compounds exhibited a significant antiviral activity.

Study of different copper(I) catalysts for the "click chemistry" approach to carbanucleosides

We compare herein the scope of three copper (I) catalysts on the synthesis of various 1,4-disubstitued-1,2,3-triazolo-carbanucleosides through a microwave (and thermic) assisted Huisgen 1,3-dipolar cycloaddition. The tetrakis(acetonitrile)copper hexafluorophosphate ([Cu(CH 3 CN)4]PF 6 ), the imidazoline(mesythyl)copper bromide (Imes)CuBr, and the copper/copper sulfate Cu(0)/CuSO 4 (II) mixture have been chosen for this study. Their influence in a catalytic amount will be analyzed according to the substituent of the alkyne, the solvent, or the heating method.