Photochemische Reaktionen von Übergangsmetall-Organyl-Komplexen mit Olefinen: IV. [4 + 5]-Cycloaddition konjugierter Diene an Tricarbonyl-η 5-2,4-pentadienyl-mangan

Abstract

Tricarbony-η 5-2,4-pentadienyl-manganese ( 1) reacts photochemically with the conjugated dienes 1,3-butadiene ( A), 2-methyl-1,3-butadiene ( 3), Z-1,3-pentadiene ( C), E-1,3-pentadiene ( D), E,E-2,4-hexadiene ( E), 2,4-hexadien-1-ol ( F), and 2,4-hexadienoic acid methyl ester ( G) in a format [4+5] cycloaddition to tricarbonyl manganese complexes with correspondingly substituted η 3:2-2,6-cyclononadiene-1l-yl ligands ( 2A–2G). The reaction 1 and A also yields tetracarbonyl-η 3- Z,E,Z-3,6,8-nontriene-2-yl-manganese ( 3A) as by-product. No cycloaddition is observed when 1 and cyclohexadiene ( H) are irradiated. The reaction yields tetracarbonyl-η 3- E-5-(4-penten-1,3-diyl)-1,3-cyclohexadiene-manganese ( 3H), dicarbonyl-η 4:3- Z,Z-5-(3-penten-1,2-diyl)-1,3-cyclohexadiene-manganese ( 4H), and dicarbonyl-η 5:2- Z-6-(3-penten-1-yl)-2,4-cyclohexadien-1-yl-manganese ( 4H′). Under ambient conditions the complexes 4H and 4H′ react with CO to give 3H. The complexes 2A–4H′ were characterised by IR and 1H NMR spectroscopy.