Photochemische Reaktionen von Übergangsmetall‐Olefin‐Komplexen 6. Bicyclo[4.4.1]undeca‐2,4,8‐triene und ihre Chrom‐ und Molybdän‐Komplexe

Abstract

Tricarbonyl(q6-l ,3,5-~ycloheptatrien)chrom(O) (1) reagiert rnit 1,3-Butadien und dessen Derivaten mit Methyl-, Vinyl-und Methoxycarbonyl-Substituenten photochemisch induziert in einer [4 + 61-Cycloaddition zu (q6-Bicyclo[4.4. I]undeca-2,4,8-trien)tricarbonylchrom(O)-Komplexen 9 -15. Die bicyclischen Liganden konnen rnit Trimethylphosphan abgespalten werden und fallen als farblose Fliissigkeiten an (22 -28). Ihre Komplexierung an Molybdan (+ 30, 31) gelingt bei der Umsetzung von Tricarbonyl(diethylenglycol-dimethylether)molybdan(O) mit Bicyclo[4.4.1]undeca-2,4,8-trien (22) und dessen 7,lO-Dimethyl-Derivat 25. 'H-NMR-und l3C-NMR-Spektren werden angegeben, sie beweisen die Konfiguration der Komplexe und der freien bicyclischen Liganden. Photochemical Reactions of Transition Metal Olefin Complexes, 6l) Bicyclo[4.4.l]undeca-2,4,8-trienes and their Chromium and Molybdenum ComplexesTricarbonyl(q6-l,3,5-cycloheptatriene)chromium(0) (1) reacts photochemically induced with 1,3-butadiene and some of its derivatives with methyl, vinyl, and methoxycarbonyl substituents in a [4 + 6]-cycloaddition to give (q6-bicyclo[4.4. l]undeca-2,4,8-triene)tricarbonylchromium(O) complexes 9-15. The bicyclic ligands can be liberated by trimethylphosphane and are obtained as colorless liquids (22 -28). Complexation to molybdenum (4 30, 31) is possible by treatment of tricarbonyl(diethy1ene glycol dimethyl ether)rnolybdenum(O) with bicyclo[4.4.l]undeca-2,4,8triene (22) and its 7,lO-dimethyl derivative 25. 'H NMR and I3C NMR spectra are reported, they prove the configuration of the complexes and free bicyclic ligands. Bei der Bestrahlung von Tricarbonyl(q-l,3,5-cycloheptatrien)chrom(O) (1) in Gegenwart von 1,3-Butadien (2) oder trans,trans-2,4-Hexadien (5) entstehen in einer [4 + 61-Cycloaddition (~-Bicyclo[4.4.1]undeca-2,4,8-trien)tricarbonylchrom(0)-Komplexe (9, 12)2). Uber die Anwendung dieses Reaktionsprinzips auf andere offenkettige, konjugierte Diene sol1 im folgenden berichtet werden. Hierbei steht die Darstellung der freien Bicyclo[4.4.l]undeca-2,4,8-triene und zwei ihrer Molybdankomplexe im Vordergrund.Derivate des 1,3-Butadiens mit Methyl-, Vinyl-und Methoxycarbonyl-Gruppen reagieren photochemisch mit l zu l : l-Addukten in guten Ausbeuten.Die Ubertragung der photochernischen [4 + 61-Cycloaddition konjugierter Diene auf die zu 1 homologen Molybdan-und Wolframkomplexe 16 und 19 gelingt nicht, vielmehr wird der Cycloheptatrien-Ligand abgespalten, und es entstehen q4-Dien-und Bis-q4-dien-Komlexe 3,4).

Progress in the Construction of Cyclooctanoid Systems: New Approaches and Applications to Natural Product Syntheses

“…Photochemically induced intermolecular cycloadditions of metal-complexed cycloheptatriene (CHT) 20 with dienophiles were first reported by Pettit, who isolated the [6 + 2]-adduct 21 with acetylenic ester (DMAD), although in poor yield, Scheme . Subsequently, Kreiter and co-workers investigated the reactivity of (CHT)Cr(CO) 3 complexes with various dienes under photochemical conditions and observed that both [6 + 2]- and [6 + 4]-cycloadditions can occur depending on the structure of the diene. Recently, Rigby and co-workers examined in detail the cycloaddition of (CHT)Cr(CO) 3 complexes with various types of alkenes with regard to selectivity and synthetic potential. ,, These cycloadditions ( 22 → 23 and 24 ) proceed in good yield, and the regioselectivity shows a marked dependence on the nature and position of the substituent on the CHT complex ( Scheme ).…”

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…In a series of papers, Kreiter et al [729][730][731][732][733][734][735] or if the reaction is run in a donor solvent (THF). 734 The authors indicate 731 that the reaction cannot be extended to other η 6 -cyclopolyene complexes such as (η 6 -1,3,5-cyclooctatriene)Cr(CO) 3 or (η 6 -1,3,5,7-cyclooctatetraene)Cr(CO) 3 and that the molybdenum and tungsten homologues of 448 do not give comparable reactions.…”

“…734 The authors indicate 731 that the reaction cannot be extended to other η 6 -cyclopolyene complexes such as (η 6 -1,3,5-cyclooctatriene)Cr(CO) 3 or (η 6 -1,3,5,7-cyclooctatetraene)Cr(CO) 3 and that the molybdenum and tungsten homologues of 448 do not give comparable reactions. In the reactions (eq 121) of (η 6 -heptafulvene)Cr(CO) 3 (463) 733 which under normal conditions add CO to give the final product 467.…”

π-Complexes of Chromium, Molybdenum and Tungsten, Excluding those of Cyclopentadienyls and Arenes

“…279 (105) via C-C bond formation at C-l and C-6 o f coordinated chpt. 296 An analogous [6 + 4] adduct is formed between (104) and buta-1,3-diene but sterically bulky dienes such as 2,3-Me 2 -buta-1,3-diene yield complexes (106) which are converted to the normal [6 + 4] adduct on reaction with CO which induces formation of a second C-C bond. 297 Analogous [6 + 4] adducts, albeit with some decomplexation of Cr(CO) 3 , are generated via photochemical reaction of buta-1,3-diene with ligand-bridged binuclear complexes (101) (M = Cr) and its heptafulvalene congener (107); 299 the addition proceeds stepwise but bis(adducts) are formed preferentially.…”