Clara Baldoli

Luminescent conjugates between dinuclear rhenium(I) complexes and peptide nucleic acids (PNA) for cell imaging and DNA targeting

New luminescent dinuclear rhenium(I) tricarbonyl complex-PNA conjugates have been synthesized through a reliable solid-phase synthetic methodology. Their photophysical properties have been measured. The most luminescent Re-PNA conjugate 7 showed interesting two-photon absorption (TPA) properties, that were exploited for imaging experiments, to demonstrate its easy uptake into living cells.

Near‐IR Emitting Iridium(III) Complexes with Heteroaromatic β‐Diketonate Ancillary Ligands for Efficient Solution‐Processed OLEDs: Structure–Property Correlations

Three NIR-emitting neutral Ir(III) complexes [Ir(iqbt)2 (dpm)] (1), [Ir(iqbt)2 (tta)] (2), and [Ir(iqbt)2 (dtdk)] (3) based on the 1-(benzo[b]thiophen-2-yl)-isoquinolinate (iqtb) were synthesized and characterized (dpm=2,2,6,6-tetramethyl-3,5-heptanedionate; tta=2-thienoyltrifluoroacetonate; dtdk=1,3-di(thiophen-2-yl)propane-1,3-dionate). The compounds emit between λ=680 and 850 nm with high luminescence quantum yields (up to 16 %). By combining electrochemistry, photophysical measurements, and computational modelling, the relationship between the structure, energy levels, and properties were investigated. NIR-emitting, solution-processed phosphorescent organic light-emitting devices (PHOLEDs) were fabricated using the complexes. The devices show remarkable external quantum efficiencies (above 3 % with 1) with negligible efficiency roll-off values, exceeding the highest reported values for solution-processible NIR emitters.

Tricarbonyl(η6arene)Chromium(0) complexes as chiral auxiliaries: Asymmetric synthesis of β-aminoesters and β-lactams by Reformatsky condensation

Abstract Highly stereoselective syntheses (e.e. > 98%) of β-aminoesters and β-lactams were accomplished using enantiomerically pure tricarbonyl (η6benzaldimine)chromium complexes in a Reformatsky type reaction promoted by ultrasound. A correlation between the configuration of complexed imines and absolute configuration of β-lactam derivatives is reported.

The first chiral racemic Fischer-type aminocarbene complex bearing a C2 symmetry amine: stereochemical characteristics and application to Michael addition reactions

Abstract The synthesis of [ trans -methyl(2,6-dimethyl)morpholinocarbene]pentacarbonylchromium(0) complex ( 3 ) is reported, together with the stereoselective Michael addition of the conjugate base of complex 3 to enones.

Transition metal (‘Fischer-type’) carbene complexes as protein labelling reagents

Abstract The electrophilic property of metallocarbenes of Fischer-type was used to label amino acid derivatives and a model protein in a regio-specific manner with a transition heavy metal complex. Hence, the reaction of (CO) 5 WC(OMe)Me ( 1 ) was shown to involve exclusively the amino group of a series of α-amino esters whether this function was carried by the α-carbon or by the side chain, leading to stable aminocarbenes. With a model protein, namely bovine serum albumin, labelling also occurred involving solely the amine function of some of its lysine residues. Coupling yield was shown to depend both on the pH where the reaction was carried out, and on the quantity of carbene. This work could find an application in the field of protein X-ray crystallography.

Enantioselective synthesis of (R)-(−)-baclofen using Fischer-type carbene anions

Abstract The antispastic drug ( R )-(−)-baclofen has been synthesized enantioselectively using a diastereoselective Michael addition reaction of the conjugate base of an enantiopure Fischer-type amino carbene to p -chloro-nitrostyrene.

Stereoselective synthesis of a new enantiopure tricyclic β-lactam derivative via a tricarbonyl(η6-arene)chromium(0) complex

Abstract The tricyclic β-lactam 5 has been synthesized both in racemic and enantiopure form starting from the enantiomerically pure tricarbonylchromium(0) complex 1. The synthetic sequence involves the stereoselective [2+2] cycloaddition of 1 with acetoxyacetylketene, followed by intramolecular aromatic nucleophilic substitution of the fluorine atom. Mechanistic pathways leading to 5 are discussed.

Michael addition of nitromethane to non-racemic chiral Cr(CO)3 complexes of ethyl cinnamate derivatives: stereoselective synthesis of (R)-(−)-baclofen

Abstract We carried out a highly stereoselective Michael addition (96% de ) of nitromethane to enantiomerically pure tricarbonyl(ethyl-4-chloro-2-trimethylsilylcinnamate)chromium(0). This reaction is the key step in the synthesis of ( R )-(−)-baclofen, a potent antispastic drug.

Stereoselective synthesis of β-sultams using chiral tricarbonyl(η6-arene)chromium(0) complexes

Abstract The reaction of (−)1R or (+)-1S-tricarbonyl(2-substituted benzaldehyde)chromium complexes with tertbutylmethanesulfonamide dianion afforded, after decomplexation and intramolecular cyclization, the enantiomerically pure N-tert-butyl-3-(2-phenyl substituted)-1,2-thiazetidine 1,1 dioxide derivatives. The hydrolytic ring opening gave the corresponding enantiopure β-aminosulfonic acid.

Tricarbonyl(η6arene)chromium(0) complexes as chiral auxiliaries. Homochiralβ-lactams synthesis “via” [2+2] cycloaddition reaction.

Abstract A highly enantioselective synthesis of β-lactams “via” a [2+2] cycloaddition reaction of homochiral tricarbonyl [ N -(2-methoxybenzylidene)aniline]chromium with ketenes is reported. Moreover the reaction of (+)-( 1 S)-tricarbonyl[4-methoxy- N -(2-methoxy cinnamylidene)aniline]chromium with acetoxy ketene gives the corresponding 4-styryl-β-lactam in good yield but with moderate stereoselection.