One-pot Cannizzaro cascade synthesis of ortho-Fused Cycloocta-2,5-dien-1-ones from 2-Bromo(hetero)aryl aldehydes

An intramolecular Cannizzaro-type hydride transfer to an in situ prepared allene enables the synthesis of orthofused 4-substituted cycloocta-2,5-dien-1-ones with unprecedented technical ease for an eight-ring carboannulation. Various derivatives could be obtained from commercially available (hetero)aryl aldehydes, trimethylsilylacetylene, and simple propargyl chlorides in good yields

Stereoselective ketone rearrangements with hypervalent iodine reagents

The first stereoselective version of an iodine(III)-mediated rearrangement of arylketones in the presence of orthoesters is described. The reaction products, α-arylated esters, are very useful intermediates in the synthesis of bioactive compounds such as ibuprofen. With chiral lactic acid-based iodine(III) reagents product selectivities of up to 73 % ee have been achieved

A mononuclear iron(III) complex with unusual changes of color and magneto-structural properties with temperature: synthesis, structure, magnetization, multi-frequency ESR and DFT study

From the reaction of 2-hydroxy-6-methylpyridine (L) with iron(II) tetrafluoroborate, a new mononuclear iron(III) octahedral complex [FeL6](BF4)3 has been isolated. The color of the complex reversibly changed from red at room temperature to yellow-orange at the liquid nitrogen temperature. Magnetization measurements indicate that iron(III) in [FeL6](BF4)3 is in a high-spin state S = 5/2, from room temperature to 1.8 K. The high-spin ground state of iron(III) is also confirmed by DFT calculations. Although the spin-crossover of the complex is not observed, X-band and multifrequency high-field/high-frequency electron spin resonance (ESR) spectroscopy shows rather uncommon iron(III) spectra at room temperature and an unusual change with cooling. Spectral simulations reveal that the S = 5/2 ground state multiplet of the complex can be characterized by the temperature independent axial zero-field splitting parameter of |D| = +2 GHz (0.067 cm−1) while the value of the rhombic parameter E of the order of some tenths MHz increases on lowering the temperature. Single crystal X-ray diffraction (SCXRD) shows that the iron(III) coordination geometry does not change with temperature while supramolecular interactions are temperature dependent, influencing the iron(III) rhombicity. Additionally, the DFT calculations show temperature variation of the HOMO–LUMO gap, in agreement with the changes of color and ESR-spectra of the iron(III) complex with temperature

A facile access to substituted benzo[a]fluorenes from o-alkynylbenzaldehydes via in situ formed acetals

Brønsted acid catalysed reaction of o-alkynylbenzaldehydes with arylalkynes in the presence of trimethyl orthoformate takes a different reaction pathway and results in benzo[a]fluorenes.</p