Synthesis and characterization of 6,6″′-bis(anthracen-9-yl)-2,2′;6′,2″;6″,2″′-quaterpyridine

New bianthracene-quaterpyridine ligand 6,6″′-bis(anthracen-9-yl)-2,2′;6′,2″;6″,2″′-quaterpyridine L has been obtained in a multistep synthesis using Suzuki–Miyaura and Stille-type coupling reactions. The dianthracene ligand L has four nitrogen-donor atoms and can form different supramolecular architectures with transition metal ions. Ligand L and intermediate compounds have been characterized by spectroscopic methods and elemental analyses. 2-(Anthracen-9-yl)-6-bromopyridine and 6-(anthracen-9-yl)-6′-bromo-2,2′-bipyridine have been also characterized by X-ray crystallography.     

Synthesis and revision of the stereochemistry of a cyclopentenone natural product isolated from ascomycete strain A23-98

The 2-propenyl-4,5-dihydroxycyclopent-2-enones 4, 10 and 14 have been synthesised in optically active form. NMR data suggest the compounds 10 and 14 (but not 4) correspond to compounds isolated from ascomycete strain A23-98.     

Preparation of perfluorocyclopentenylmetal species and their cross-coupling reaction with electrophiles—Remarkable accesses to versatile perfluorocyclopentene derivatives

On treating perfluorocyclopentene with bis(tributylstannyl)cyanocuprate in THF at −78 °C for 1 h, perfluorocyclopentenylstannane was obtained in good yield. The reaction of the fluorinated vinylstannane with n-BuLi in THF at −78 °C for 1 h, followed by addition of carbonyl compounds, gave the corresponding allyl alcohols in good yields. On the other hand, Pd(0)-catalyzed cross-coupling reaction of perfluorocyclopentenylstannane with benzyl chloroformate in THF at reflux temperature for 2 h proceeded smoothly to form the decarbonated coupling product in high yield.     

Use of Stille-type cross-coupling as a route to oligopyridylimines

The new tin reagents, 2-(n-Bu₃Sn)-6-{C(R)OCH₂CH₂O}-C₅H₃N, (R=H a, Me b), have been employed in Stille-type cross-coupling reactions with a range of oligopyridylbromides generating, following a facile deprotection step, a series of formyl- and acetyl-functionalised oligopyridines. Condensation reactions with 2,6-diisopropylaniline has allowed access to families of novel sterically bulky multidentate N,N,N,N (tetradentate), N,N,N,N,N (pentadentate), N,N,N,N,N,N (sexidentate) and N,N,N,N,N,N,N (heptadentate) nitrogen donor ligands. This work represents a straightforward and rapid synthetic route for the preparation of oligopyridylimines, which are expected to act as useful components for the self-assembly of polymetallic complexes.