Four palladium chelate complexes with S‐ or Se‐containing substituted salicylaldehyde Schiff‐base derivatives have been synthesized. Spectroscopic and crystallographic data indicate that, in the complexes, the deprotonated salicylaldehyde ligand is bound to the metal in an O,N,S (or Se)‐terdentate coordination mode, forming one six‐ and one five‐membered chelate ring. The complexes are thermally and air stable and efficiently catalyze the Suzuki–Miyaura cross‐coupling of aryl bromides with phenylboronic acid in air.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Regio- and stereoselective reactions accompanied by rearrangements with ring extension or contraction.

Regio- and stereoselective ring-opening reaction of 2-bromomethyl-1,3-thiaselenole with thiols proceeded as nucleophilic attack at the selenium atom of seleniranium intermediate affording unsaturated selanyl sulfides, (Z)-CH2=CHSCH=CHSeSR, in up to 93% yield. Dithiols were involved in this reaction giving symmetrical polyunsaturated compounds with two S–Se bonds in 70–75% yields. Efficient synthesis of 2-(organylsulfanyl)-2,3-dihydro-1,4-thiaselenines in 69–96% yields was developed by the acid-catalyzed cyclization of the unsaturated selanyl sulfides. Mild reaction conditions (room temperature) and short reaction times are important features of this methodology.