Aluminum oxide catalyzed isomerization of acylated cycloalkenes

Hudlický, Tomáš; Srnak, T. Z.

doi:10.1016/s0040-4039(01)81902-x

Cited by 30 publications

(10 citation statements)

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“…The titanium tetrachloride promoted [3+2] cycloaddition of allylsilanes 1d, 1g, and 1i with 1-acetylcycloalkenes 2 and 7 provided silylbicyclo[n. 3.0]alkanes 6 and 8 (Scheme 3 and Table 2). 14,24,51 1-Acetylcycloalkenes 2 were prepared by either Friedel-Crafts acylation of the corresponding cycloalkenes 52,53 or Rupe rearrangement of the 1-ethynylcycloalkanols. [54][55][56] The X-ray analyses of products 6ad-6cd confirmed that the cycloaddition of allyltriphenylsilane (1d) afforded the anti-diastereoisomers with complete stereoselectivity, irrespective of the ring size of 1-acetylcycloalkenes 2 (Figures 2-4).…”

Section: Biographical Sketchesmentioning

confidence: 99%

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Cycloadditions of Allylsilanes - Part 22.¹ Stereoselective Synthesis of Cyclopentanes and Cyclobutanes by Lewis Acid Promoted [3+2] and [2+2] Cycloadditions of Allylsilanes

Schmidt¹,

Knölker²

2010

Synlett

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Section: Biographical Sketchesmentioning

confidence: 99%

“…Moreover, with enones 7, which are readily available by literature procedures, 53,[57][58][59][60] it was demonstrated that the [3+2] cycloaddition of allylsilanes can be applied to the diastereoselective construction of bicyclic ring systems containing two contiguous quaternary carbon atoms.…”

Section: Biographical Sketchesmentioning

confidence: 99%

Cycloadditions of Allylsilanes - Part 22.¹ Stereoselective Synthesis of Cyclopentanes and Cyclobutanes by Lewis Acid Promoted [3+2] and [2+2] Cycloadditions of Allylsilanes

Schmidt¹,

Knölker²

2010

Synlett

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“…Compounds 5a and 5b were available from 1-acetyl-1-cyclopentene (7), [9] as outlined in Scheme 2 (TMS ϭ trimethylsilyl). A Sakurai reaction yielded the thermodynamically preferred trans-substituted cyclopentane 8a as the major product (trans/cis ϭ 80:20).…”

Section: Stereoselective Preparation Of the Substrates 5 Andmentioning

confidence: 99%

“…In the case of the six-membered 1-acetyl-1-cyclohexene (9), [9a] the Sakurai reaction yielded the kinetically favored cis-cyclohexane 10b (cis/trans ϭ 90:10), which did not epimerize as readily as its five-membered analogue (Scheme 3). The subsequent methylenation proceeded smoothly and gave the desired cis-substituted product 6b after chromatographic purification (cis/trans ϭ 96:4).…”

Section: Stereoselective Preparation Of the Substrates 5 Andmentioning

confidence: 99%

Stereoselective Photochemical Synthesis and Structure Elucidation of 1-Methyl-Substituted Tricyclo[6.2.0.02,6]decanes and Tricyclo[7.2.0.02,7]undecanes

Bach

Spiegel

2002

Eur. J. Org. Chem.

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The trans-and cis-substituted 2-allyl-1-(2-propenyl)cyclopentanes 5a (47% yield) and 5b (33% yield) as well as the trans-and cis-substituted 2-allyl-1-(2-propenyl)cyclohexanes 6a (48% yield) and 6b (64% yield) were synthesized from the corresponding 1-acetyl-1-cycloalkenes. Their intramolecular, Cu-catalyzed [2+2] photocycloaddition reaction was studied in ether as the solvent. The reaction proceeded with excellent facial diastereoselectivity. The trans-cycloalkanes 5a and 6a exclusively yielded the trans-anti-cis products 11a (80%)The intramolecular Cu-catalyzed [2ϩ2] photocycloaddition of 1,ω-dienes is a powerful method for the construction of bicyclic compounds. [1] The facial diastereoselectivity of the reaction can be controlled by a stereogenic center within the carbon chain [2] or by chiral auxiliaries. [3] Attempts to induce significant enantiofacial differentiation by chiral catalysis have encountered only limited success. [3] Recent applications of the intramolecular Cu-catalyzed [2ϩ2] photocycloaddition have centered on the synthesis of multiply substituted, naturally occurring cyclopentanes and cyclobutanes. [4] These are formed from the primary photoadducts through subsequent ring-opening or rearrangement reactions. [5] We became interested in the preparative use of the [2ϩ2] photocycloaddition in connection with our studies on the stereoselective synthesis of biologically active 3-azabicyclo[3.2.0]heptanes from amino acid derived diallylamines. [6] In this context it turned out that N-allyl-4-ethenyloxazolidinones 1 react with perfect facial diastereoselectivity to afford the corresponding heterocyclic tricyclo[6.2.0.0 2,6 ]decanes 2 (Scheme 1; Tf ϭ trifluoromethanesulfonate). The stable Cu(OTf) 2 proved to be a suitable precursor for the catalytically active Cu I . [2e] [6b] The only other tricyclic products that have previously been synthesized by means of Cu-catalyzed photocycloaddition reactions are 2-hydroxytricyclo[6.2.0.0 2,6 ]decanes (e.g., 4), which are formed from the corresponding dienes [a] 645 and 12a (80%), whereas the cis-cycloalkanes 5b and 6b yielded the cis-syn-cis products 11b (77%) and 12b (88%). The structures of the products 11a and 12a were elucidated by NMR spectroscopy. The configuration assignments of compounds 11b and 12b were confirmed by independent syntheses of these compounds. Stereoselective hydrogenation of the unsaturated tricycloalkenes 13 and 14 gave access to the tricycloalkanes 11b (69%) and 12b (79%).Scheme 1. Previous syntheses of hetero-and carbocyclic tricyclo-[6.2.0.0 2,6 ]decanes by Cu-catalyzed [2ϩ2] photocycloadditions (e.g., 3; Scheme 1). [2c] In the latter case, the high facial diastereoselectivity was attributed to the known binding affinity of Cu I to hydroxy groups. [2a] The coordination of the two olefinic double bonds to the metal ion forces the carbonϪcarbon bond formation at the vinylic carbon atom to occur from its (Si) face. Analogous stereochemical results were obtained in the synthesis of 2-hydroxytricyclo-[7.2.0.0 2,7 ]undecanes ...

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“…Experimentelles 2-(2-Methylcyclohex-2-enyl)-1-phenylpropan-2-ol: Zu einer Lösung von 1-Acetyl-(2-methylcyclohex-2-en) [10] (6.0 g, 43.0 mmol) in wasserfreiem THF (100 mml) wurde bei 0 8C unter Stickstoff Benzylmagnesiumchlorid (32.6 ml, 2.5 m) in THF gegeben. Nach 16 h Rühren bei 20 8C wurde die Reaktion durch Zugabe gesättigter NH 4 Cl-Lösung (10 ml) beendet.…”

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