Photochemische Reaktionen von Übergangsmetall‐Olefin‐Komplexen, 10. [4 + 6]‐Cycloaddition konjugierter Diene an Tricarbonyl [1 – 6‐η‐(8,8‐dimethylheptafulven)]chrom(0)

Abstract

Tricarbonyl[ 1 -6-q-(8,8-dimethylheptafulven)]chrom(O) (2) reagiert photochemisch induziert rnit konjugierten Dienen auf zwei unterschiedliche Weisen. Mit 1,3-Butadien (3), trans-I ,3-Pentadien (4), trans,trans-2,4-Hexadien (5) und 1,3-Cyclohexadien (6) werden Tricarbonyl(q6-1 l-isopropyliden bicyclo[4.4.1]undeca-2,4,8-trien)chrom(O)-Komplexe 11 -14 erhalten. Dagegen bilden 2,3-Dimethyl-l,3-butadien (9) und 1,2-Dimethylencyclohexan (10) rnit 2 neuartige {q3:5-[1-(3-Buten-1,2-diyl)-7-isopropylidencycloheptadienyl] dicarbonylchrom-Komplexe 20,21. 2-Methyl-l,3butadien (7) und 2-Methyl-1,3-pentadien (8) zeigen beide Reaktionsmoglichkeiten. 18 -20 addieren Kohlenmonoxid rnit nachfolgendem RingschluR zu den [4 + 6]-Cycloaddukten 15 -17. Von 11 -16 lassen sich die di-und tricyclischen Tetraen-Liganden 22-27 mit P(OCH,), abspalten. Die Konstitution der isolierten Komplexe und Kohlenwasserstoff-Liganden wurde spektroskopisch ermittelt. Zusatzlich wurde die Kristall-und Molekulstruktur von 14 rontgenographisch bestimmt. Photochemical Reactions of Transition Metal Olefin Complexes, 10') [4 + 61 Cycloaddition of Conjugated Dienes to TricarbonylI 1 -6-q-(8,8-dimethylheptafulvene)]chromium(O) Tricarbonyl[l -6-~-(8,8-dimethylheptafulvene)]chromium(0) (2) reacts photochemically induced with conjugated dienes in two different ways. With 1,3-butadiene (3), trans-I ,3-pentadiene (4), trans,trans-2,4-hexadiene (S), and 1,3-~yclohexadiene (6) tricarbonyl(q'-l l-isopropylidenebicyclo[4.4.l]undeca-2,4,8-triene)chromium(O) complexes 11 -14 are obtained. In contrast, 2,3-dimethyl-l,3-butadiene (9) and 1,2-dimethylenecyclohexane (10) form with 2 novel [ l-(3-butene-l,2-diyl)-7-isopropylidenecycloheptadienyl] f dicarbonylchromium complexes 20,21. 2-Methyl-l,3-butadiene (7) and 2-methyl-l,3-pentadiene (8) show both types of reactions. 18 -20 add carbon monoxide with successive ring closure to give the [4 + 61 cycloadducts 15 -17. From 11 -16 the di-and tricyclic tetraene ligands 22-27 are displaced by P(OCH,), in good yields. The constitutions of the isolated complexes and hydrocarbon ligands were elucidated by spectroscopic means. In addition the crystal and molecular structure of 14 was determined by X-ray structure analysis. _________ _ _ _ _ _~ _ _ _ _ _ _ _ _ _~ Die photochemische Reaktion von Tricarbonyl(q6-l ,3,5-~ycIoheptatrien)chrom(O) (1) rnit offenkettigen l,3-Dienen fiihrt in einer [4 + 61-Cycloaddition zu Tricarbonyl-(q-bicyclo[4.4.l]undeca-2,4,8-trien)chrom(O)-Komple~en*~~~. Cyclische Diene wie 1,3-Cyclohexadien und Spiro[4.4]nona-l,3-dien reagieren dagegen rnit 1 unter [2 + 41-Cycloaddition mit nachfolgender 1,5-H-Verschiebung bzw. unter [ 2 + 61-Cycloaddi-tion4). Dieses Reaktionsprinzip erlaubt einen leichten Zugang zu bi-und tricyclischen Trienen, die auf klassischem Weg bislang noch nicht synthetisiert wurden. 0 VCH Verlagsgesellschaft mbH, D-

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. This provides conclusive evidence that the connection of the seven-membered ring and the diene in the coordination sphere is not a concerted but rather a stepwise process.…”

“…, the intermediate thermolabile dicarbonyl complexes 466 have been isolated, 733 which under normal conditions add CO to give the final product 467. This provides conclusive evidence that the connection of the seven-membered ring and the diene in the coordination sphere is not a concerted but rather a stepwise process.…”

“…In a series of papers, Kreiter et al. − have reported on the photochemically induced [6+4] cycloaddition of conjugated dienes 461 to (η 6 -cycloheptatriene)- ( 448 ), (η 6 -heptafulvene)- and (η 6 -heptafulvalene)tricarbonylchromium moieties. [An overview is given in ref .]…”

Metal-promoted higher-order cycloaddition reactions. Stereochemical, regiochemical, and mechanistic aspects of the [6.pi. + 4.pi.] reaction

“…m), 5.55 (1 H, ddd, 7, = 48 Hz, J2 = 8 Hz, 73 = 2 Hz), 3.4-3.S (2 H, m), 1.2 (9 H, s); l9F NMR -149.3 ppm (m); l3C NMR (ppm) 128-125 (Carom), 93.6 (d, '7cf = 180 Hz), 73.5 (s, (CH3)3C), 66.4 (d,27CF = 25 Hz), 27.3 (s); MS m/e 123 (PhCHFCH2+), 109 (PhCHF+). Anal. Caled for C12Hl7FO: C, 73.47; H,8.67.…”