Photocycloaddition of Cyclohex‐2‐enones to Tetramethoxyethylene: Formation of 2,2,3,3‐Tetramethoxy‐1‐oxaspiro[3.5]non‐5‐enes

Cruciani, G.; Rathjen, H. J.; Margaretha, P.

doi:10.1002/hlca.19900730410

Cited by 12 publications

(2 citation statements)

References 19 publications

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“…62 The synthesis of 2,8-didehydronoradamantan-9-one (167) was performed starting from brend-4-en-2-one (164) The enantiospecific ODPM transformation of bridged 0,7-unsaturated ketones has paved the way to a ready access to enantiomeric target compounds.480 C. Azadl-r-methane Rearrangements Horspool and colleagues have studied in great detail the effect of substituents with respect to the formation of cyclopropylimines from a,/3-unsaturated imines or azadi-ir-methane (ADPM) systems.54 It was found that electron-withdrawing groups located on the nitrogen atom have a beneficial influence on the ADPM rearrangement. Thus, the acetoxy-substituted imine 168 afforded compound 169 in the presence of suitable sensitizers. 55 The similar ADPM system 170 led to the cyclopropylimine 171, while the compound lacking the methyl group only gave cis-trans isomerization thereby indicating the importance of the functionality pattern (eq 27).56 168 169 (27) 177 178 179…”

Section: Dl-ir -Methane-type Rearrangementsmentioning

confidence: 99%

“…A short synthesis of the fungal metabolite hirsutene (382) containing the cis-an£i-cis-tricyclo[6.3.0.04,8]undecane ring system was reported by Weedon. 169 The skeleton was assembled by a de Mayo reaction of 2-methylcyclopent-2-en-l-ol (376), an 5,5-dimethylcyclohexane-1,3-dione (377) (eq 65). The bicyclic compounds 380 and 381 (1:2) were generated from the initially formed cyclobutanes 378 and 379, respectively, (86%) by spontaneous retro-aldol ring opening.…”

Section: B [2 + 2] Photocycloadditionsmentioning

confidence: 99%

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Photochemical strategies for the construction of polycyclic molecules

Keukeleire¹,

He²

1993

Chem. Rev.

133

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Section: Dl-ir -Methane-type Rearrangementsmentioning

confidence: 99%

Section: B [2 + 2] Photocycloadditionsmentioning

confidence: 99%

Photochemical strategies for the construction of polycyclic molecules

Keukeleire¹,

He²

1993

Chem. Rev.

133

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Wechselwirkung von Triplett‐3‐Methylcyclohex‐2‐en‐1‐on mit Malein‐ und Fumarsäuredinitril ‐ Hinweise auf die direkte Bildung von Triplett‐1,4‐Diradikalen bei [2 + 2]‐Photocycloadditionen ohne Exciplex‐Zwischenstufen

1991

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Alken‐Enon‐Exciplexe können als Zwischenstufen bei der [2 + 2]‐Cycloaddition von Fumarsäuredinitril an Triplett‐3‐Methylcyclohex‐2‐en‐1‐on ausgeschlossen werden. Aufgrund der experimentellen Befunde ist statt dessen die Triplett‐1,4‐Diradikal‐Zwischenstufe 1 favorisiert, die rasch durch Rotation um die neu gebildete Einfachbindung isomerisiert und zu den entsprechenden Cycloaddukten reagiert.

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The Mechanism of Interaction of Triplet 3‐Methylcyclohex‐2‐en‐1‐one with Maleo‐ and fumarodinitrile: Evidence for Direct Formation of Triplet 1,4‐Biradicals in [2 + 2] Photocyclo‐ additions without the Intermediacy of Exciplexes

Schuster

Heibel

Woning

1991

Angew. Chem. Int. Ed. Engl.

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which has elsewhere['41 manifested a special coordination ability. Irradiation (d = 289 nm) of [Cr(C0),(q4-nbd)] and ECO in 2-methylpentane at -40°C affords mer-and juc-[Cr(C0),(q4-nbd) (q2-eco)], which are easily distinguished on the basis of their CO stretching bands (rner complex, f [cm-'] = 1997(m), 1925 (sst); fac complex < [cm-'] = 1968, 1904, 1876). The mer complex, which is more stable, is the only observed product at room temperature. In order to determine the quantum yield (@ = 0.18 at 300 nm, 0.1 1 at 365 nm), its formation was followed quantitatively by IR spectroscopy. If this reaction is assumed to serve as a model for the generation of the catalytically active [Cr(CO),] complex (Qind), then the relation eta, = Gind x (turnovers) gives a rough estimate of 10 to 20 for the quantum yield of the photocatalytic hydrogenation of norbornadiene (Qca,). The experimentally determined values (1.9,['] ca. 0.3[,') are considerably lower, probably because the active [Cr(CO),] complex generated in situ is rapidly transformed into inactive [Cr(CO),(q4-nbd)] by the CO still present in the system. The stability of [M(C0),(q4-nbd)(q2-olefin)] complexes increases markedly in the series Cr < Mo < W. As a result, the catalytically active species is trapped by excess substrate (NBD) as [M(CO), (q4-nbd)(q2-nbd)] in the cases of tungsten and molybdenum.['0] The analogous chromium complex, by contrast, has not yet been detected. Thus, the drastic decrease in the catalytic activity in the series Cr $ Mo > WI3] is readily explained.In analogy to the hydrogenation, norbornadiene can also be hydrosilylated with silanes (R,SiH), both photocatalytically with [Cr(CO), (q4-nbd)] and in the dark with 1. As we will report in detail elsewhere, both variants afford endo 1,2-, exo 1,2-, and homo 1,4-adducts with comparable product distributions. Experimental ProcedurePreparation of 1: [Cr(C0),(q4-nbd)] (1.00 g, 3.9 mmol) was irradiated in 200 mL of ethene-saturated pentane at -50°C in an immersion lamp apparatus (Solidex glass, i . 2 280 nm; Philips HPK 125-W Hg lamp) for about 3 h, until the starting material (Cco [cm-'1 = 2043, 1961, 1946, 1917) had largely reacted. The temperature was maintained at I -30°C during workup. After addition of about 2 g of silica gel (to absorb readily decomposable by-products), the solution was stirred for several minutes and then evaporated to dryness under vacuum. The residue was extracted into 3 x 10 mL of ethene-saturated pentane, transferred to a column (silica gel 60, Merck; 2 x 15 cm), and eluted with additional solvent. The first of the two yellow fractions was concentrated under vacuum to about 50mL and cooled to -78°C whereupon pure mer-[Cr(C0),(q4-nbd)(q2-ethene)] (0.46 g, 46 %) crystallized out. M.p. = 46°C; correct elemental analysis (C, H, Cr); IR (n-hexane): F[cm-'] = 2005(m), 1933 (sst) (CO). 'H NMR (400 MHz, C,D,, 243 K): 6 = 0.85 (m, 2 H), 1.85 (s, br, 4 H, ethene), 3.00 (s, br, 2 H), 3.16 (s, br, 2 H), 3.89 (s, br, 2 H). "C NMR (100.6 MHz, C,D,, 243 K): 6 = 47.41 (CH), 52.78 (ethene)...

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Photocycloaddition of Cyclohex‐2‐enones to Tetramethoxyethylene: Formation of 2,2,3,3‐Tetramethoxy‐1‐oxaspiro[3.5]non‐5‐enes

Cited by 12 publications

References 19 publications

Photochemical strategies for the construction of polycyclic molecules

Photochemical strategies for the construction of polycyclic molecules

Wechselwirkung von Triplett‐3‐Methylcyclohex‐2‐en‐1‐on mit Malein‐ und Fumarsäuredinitril ‐ Hinweise auf die direkte Bildung von Triplett‐1,4‐Diradikalen bei [2 + 2]‐Photocycloadditionen ohne Exciplex‐Zwischenstufen

The Mechanism of Interaction of Triplet 3‐Methylcyclohex‐2‐en‐1‐one with Maleo‐ and fumarodinitrile: Evidence for Direct Formation of Triplet 1,4‐Biradicals in [2 + 2] Photocyclo‐ additions without the Intermediacy of Exciplexes

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