Novel one-pot synthesis of 5-alkenyl-15-alkynylporphyrins and their derivatisation to a butadiyne-linked benzoporphyrin dimer

5-Alkenyl-15-alkynylporphyrins have been obtained unexpectedly by [2 + 2] acid-catalyzed condensation of dipyrrylmethane and TMS propynal in addition to 5,15-dialkynylporphyrin, and the unsymmetrical porphyrin can be converted to a butadiyne-linked dimer by selective desilylation of the alkynyl TMS.     

Ligand dependence of pi-complex character in disilene-palladium complexes

The synthesis and structures of new 16-electron disilene palladium complexes with 2,6-dimethylphenyl isocyanide and phenyldimethylphosphine ligands [L(1)L(2)Pd{(t-BuMe(2)Si)(2)Si=Si(SiMe(2)Bu-t)(2)}, where L(1) = L(2) = PhMe(2)P; L(1) = (cyclohexyl)(3)P, L(2) = 2,6-dimethylphenyl isocyanide; L(1) = L(2) = 2,6-dimethylphenyl isocyanide] are described. Comparison of the X-ray structural parameters around the disilene moiety among these complexes and related bis(trimethylphosphine)(disilene)palladium and 14-electron (tricyclohexylphosphine)(disilene)palladium revealed that the pi-complex character is sensitive to the residual ligands and increases with decreasing the strength of sigma-donation from the ligands.     

Polymere, die Benzimidazol- und Chinazolindion-Einheiten in der Hauptkette enthalten

Ohne Zusammenfassung     

Syntheses of (±)-aklavinones : Application of the stereocontrolled “zipper” bicyclo cyclization reaction

Efficient syntheses of(1+-)-aklavinones; (±)-aklavinone (1), (±)-auramycinone (2), and (±)-13-methylaklavinone (3), are described. A key process of the tetracyclic ring construction in these syntheses is ia stereocontrolled “zipper” bicyclo-cyclization using a KH-Kryptofix 222 (4,7,13,16,21,24-hexaoxa-1.10-diazabicyclo [8.8.8]hexacosane) cryptate as a base. The reaction mechanism is discussed, too