A new synthetic approach to the bicyclo[3.2.1]octane ring system, based on intramolecular photocycloaddition involving cyclopentane-1,3-dione enol esters

Barker, Andrew; Begley, Michael J.; Mellor, Michael; Otieno, Dismas A.; Pattenden, Gerald

doi:10.1039/p19830001893

Cited by 14 publications

(6 citation statements)

References 1 publication

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“…It is believed that this rearrangement is intermolecular in the presence of basic catalysts,24a but intramolecular in the presence of Lewis acids 24c. Some authors proposed that the acid-catalyzed O−C isomerization of acyloxy vinyl ketones is a variant of the Fries rearrangement. To clarify this problem a cross-isomerization experiment of a pair of enol esters ( 13 ) with different ring structures and side chains using either acidic (AlCl 3 , ZnCl 2 ) or basic (NaOAc, K 2 CO 3 , DMAP) catalysts has been performed .…”

Section: Synthesis Of Cyclic β-Triketones: O−c Isomerizationgeneral...mentioning

confidence: 99%

Chemistry of 2-Acylcycloalkane-1,3-diones

1999

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Section: Synthesis Of Cyclic β-Triketones: O−c Isomerizationgeneral...mentioning

confidence: 99%

Chemistry of 2-Acylcycloalkane-1,3-diones

1999

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“…This novel isomerisation was first investigated in detail by Elliott: and later by ourselves.' The required 2-prop-2-enyl substituted 4-hydroxycyclopent-2-enones (10) are most conveniently obtained starting from the corresponding pketo esters (12) or the triethoxycyclopentenone ( 13) by procedures which are well documented? Heating the hydroxycyclopentenones in the presence of hot methanolic sodium methoxide then produced the unsymmetrical diones (1 l a d ) in good yield.…”

Section: Ho ( 1 )mentioning

confidence: 99%

The synthesis of 4-prop-2-enyl substituted cyclopentane-1,3-dione enol esters, and an investigation of their structures by N.m.r. spectroscopy

Barker¹,

Pattenden²

1983

J. Chem. Soc., Perkin Trans. 1

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“…selective formation of tricyclo[3.2. l.03~6]octan-2-ones from 5-(prop-2-enyl)cyclopent-2-enones [ 17-1 91 us. formation of mixtures of such compounds and the isomeric tricyclooctan-7-ones from cyclopent-2-enones bearing alkyl groups at C(2') of the ally1 side chain at C(5) [17] [2&22] has its precedents in the literature, but has usually not been discussed further.…”

mentioning

confidence: 99%

Regiochemical Trends in Intramolecular [2 + 2] Photocycloadditions of 6‐(prop‐2‐enyl)cyclohex‐2‐enones and 5‐(prop‐2‐enyl)cyclopent‐2‐enones

Cruciani

Margaretha

1990

Helvetica Chimica Acta

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Dedicated to Prof. H . F. Mark, Brooklyn, in admiration and reverence on the occasion of his 95th birthday (12.X11.89) ~~~ ~~~The effect of substituents (X = H, Me, or F at C(6), R = H or Me at C(2') of the ally1 side chain) on the photoisomerization (2 = 350 nm) of 6-allylcyclohex-2-enones 1 in MeCN is studied. Subslituents X control the overall efticiency of intramolecular [2 + 21 photocycloadduct formation (@: Me > F > H) but do not exercise an influence on the orientation of addition of the exocyclic double bond to the enone C=C bond. In contrast, replacement of the prop-2-enyl (R = H) by a 2-methylprop-2-enyl (R = Me) side chain causes a change in the tricyclo[3.3.1 .O2,']nonan-6-one 4 us. tricyclo[4.2. 1.03.8]nonan-7-one (5) product ratio from 1OO:O (R = H) to roughly 2:l (R = Me) but has almost no bearing on the relative rates of conversion of 1 to products. For C(6)-unsubstituted enones laa and 1ba (X = H), the efficiency of cyclization becomes low enough so that lumiketone rearrangement to bicyclohexanones 6 and 3-isopropylcyclopent-2-enones 9 becomes competitive. Introduction. -Applications of intramolecular enone/olefin photocycloadditions in organic synthesis have been the subject of three recent reviews [l] [2]. As stated by one of the authors [l], there is still much that is not well understood about the mechanistic aspects of this important reaction. For cyclic enones bearing a side chain with an additional C=C bond at either C(2) or C(3), the regiochemistry seems to be controlled by the number of C-atoms in the chain connecting the two C=C bonds. Similarly, Agosta and coworkers showed in their studies devoted to the regiochemical control of intramolecular photochemical reactions of carbonyl-substituted hexa-l$dienes and hepta-l,6-dienes [3-61 that in such molecules two-atom bridges usually lead to crossed adducts while bridges with three atoms generally produce straight adducts. The empirical so-called 'rule of five' stating that the regioisomer formed via a five-membered cyclic biradical is always formed preferentially has been partially overemphasized in explaining these results [7], inter alia as it does not take into consideration the formation of an exciplex between the excited enone moiety and the additional double bond prior to biradical formation. Exciplexes have been shown to be the primary intermediates in both inter- [8] [9] and intramolecular [lo] enone/olefin photocycloadditions. In a study on carbonyl-substituted hepta-1,6-dienes, Agosta and coworkers [5] discussed the possibility of initial 1,7-bonding and also mentioned that the regiochemical behaviour of substrates related to 5-allylcyclopent-2-enones and 6-allylcyclohex-2-enones had proven complicated.

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A new synthetic approach to the bicyclo[3.2.1]octane ring system, based on intramolecular photocycloaddition involving cyclopentane-1,3-dione enol esters

Cited by 14 publications

References 1 publication

Chemistry of 2-Acylcycloalkane-1,3-diones

Chemistry of 2-Acylcycloalkane-1,3-diones

The synthesis of 4-prop-2-enyl substituted cyclopentane-1,3-dione enol esters, and an investigation of their structures by N.m.r. spectroscopy

Regiochemical Trends in Intramolecular [2 + 2] Photocycloadditions of 6‐(prop‐2‐enyl)cyclohex‐2‐enones and 5‐(prop‐2‐enyl)cyclopent‐2‐enones

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