New tetrathia[7]helicene-based (7-TH-based) gold(I) complexes 6 and 7 have been readily prepared by reaction of the respective phosphine ligands 2 and 3 with Au(tht)Cl in a 1:1 and 1:2 molar ratio, respectively. These complexes have been fully characterized by analytical and spectroscopic techniques as well as quantum chemical calculations. The molecular structure of dinuclear complex 7 has been determined by single-crystal X-ray diffraction, showing a gold-gold interaction of 3.1825(3) Å and a significant contraction of the 7-TH total dihedral angle. Au(I) complex 7 displays luminescence emission at room and low temperature in diluted solution and in the solid state. Quantum chemical calculations show that the luminescence emission at room temperature is primarily due to slightly perturbed fluorescence emission from purely ππ* excited states of the conjugated helicene scaffold. At 77 K phosphorescence emission is displayed as well. Preliminary studies on the use of 6 and 7 as catalysts in typical Au(I)-catalyzed cycloisomerizations have demonstrated the reactivity of these systems in the intramolecular allene hydroarylations and the hydroxycarboxylation of allene-carboxylates.

Enantiomerically pure thiahelicenes displaying a terminal phosphole unit and a stereogenic phosphorus center have been prepared by oxidative photocyclization of a diaryl-olefin precursor. Starting from one of these phosphathiahelicene oxides, the corresponding trivalent phosphine-Au(I) complex is obtained with complete diastereoselectivity. It affords a new, excellent precatalyst for the enantioselective cycloisomerization of N-tethered enynes (up to 96 % ee).

Hydrophilic SPION were decorated with PNA decamers by SH/maleimide clickreaction as potential MRI and hyperthermia agents, and PNA carriers.

Two new chiral tetrathia[7]helicene (7‐TH) based tertiary phosphine oxides (±)‐2b and (±)‐2c, bearing two substituents on the phosphorus atoms with different steric and electronic properties, have been synthesised and fully characterised by means of analytical and spectroscopic techniques. The resolution of (±)‐2a–c into their antipodes was accomplished by HPLC separation on a chiral stationary phase, and their chiroptical properties were investigated by CD spectroscopy. The behaviour of 2a–c as organocatalysts was assessed in representative reactions mediated by tri‐ or tetrachlorosilane. 7‐TH‐based phosphine oxides 2a and 2b promoted both ketoimine reduction and stereoselective carbon–carbon bond formation in good chemical yields and diastereoselectivity, albeit with low enantioselectivity, thus opening the way to the development of a novel class of enantiopure helical‐based phosphorus organocatalysts.

The FeCl3-mediated cyclization of a,a0-disubstituted Z-alkenes 1 is reported as a general and non-photochemical route to synthesize benzo[1,2-b:4,3-b0]dithiophene (BDT) derivatives 2, achievable in good yields starting from cheap and easily available materials. The influence of the temperature and the nature of the substituents on the scope and limitations of this methodology is also reported

Substituted phosphathiahelicenes have been prepared via a straightforward two-step procedure involving the regioselective bromination of a preformed helical scaffold, followed by palladium catalyzed coupling reactions. The new helicenes have been used as ligands in gold(i)-catalyzed [4+2] cyclizations of 1,6-enynes. The resulting dihydro-cyclopenta[b]naphthalene derivative was obtained in excellent yields and with up to 91% ee.

No abstract

Chiral helical-based phosphanes are challenging and promising ligands, with a great potential for the generation of both organic and organometallic catalysts. We report here the preparation of novel chiral thiahelicene-based alkyl phosphanes, isolated and characterized as air-stable borane adducts, and the investigation of their experimental and theoretical (chir)optical properties. X-ray characterization of a mono- and a disubstituted derivative as a racemic mixture has been performed, which confirms the influence of the number and nature of substituents on the flexibility of the helix. In addition, the absolute configuration inferred from CD spectra of the two enantiomers of a diborane complex has been established from X-ray analysis. State-of-the-art quantum chemical calculations of vibrationally resolved spectra allow, for the first time, for an unambiguous assignment of the experimentally observed peaks in linear absorption and circular dichroism spectra to excited electronic states of this class of thiahelicene phosphorus derivatives.