Strategy for the Preparation of Allenes from α,β-Unsaturated and Saturated Ketones via Enol Phosphates

Brummond, Kay M.; Dingess, E. A.; Kent, Joseph L.

doi:10.1021/jo9610265

Cited by 46 publications

(22 citation statements)

References 7 publications

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“…Nonaflation of 1‐Trimethylsiloxycyclododec‐1‐ene (1g): The reaction was performed according to Method A, by treatment of 1g (1.27 g, 5.00 mmol; E / Z = 82:18) with [(Me 2 N) 3 S][SiMe 3 F 2 ] (0.65 mmol, 0.25 molar in THF/CH 2 Cl 2 ) and NfF (3.02 g, 10.0 mmol), followed by kugelrohr distillation at 120 °C/0.001 mbar to afford a mixture of products (1.34 g). Repeated fractional distillation at 80 °C/2 mbar furnished a fraction (0.890 g) enriched in nonaflate 3g but complete separation was not achieved, and the content of the resulting mixture of products, established by GC‐MS, was: ( E )‐ 3g (29%), ( Z )‐ 3g (14%), cyclododecyne40 (36%), cyclododeca‐1,2‐diene40 (< 1%) and cyclododecanone (20%). ( E )‐Cyclododec‐1‐enyl Nonaflate (3g): 1 H NMR (300 MHz): δ = 1.20−1.74, 2.10−2.47 (2 m, 20 H, 3‐H − 12‐H), 5.49 (t, J = 8.3 Hz, 1 H, 2‐H).…”

Section: Methodsmentioning

confidence: 99%

An Expedient and Stereoselective Synthesis of Alkenyl Nonaflates from Silyl Enol Ethers: Optimization, Scope and Limitations

2002

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The fluoride-catalysed reaction between silyl enol ethers 1 and nonafluorobutanesulfonyl fluoride (NfF) has been optimized, resulting in an expedient synthesis of the corresponding alkenyl nonaflates 3. Tetra-n-butylammonium fluoride, dried either with molecular sieves or with potassium fluoride, and potassium fluoride in the presence of dibenzo-18-crown-6 were the best and most practical catalysts for this process. The reaction allows the synthesis of a wide variety of cyclic and acyclic alkenyl nonaflates 3 in good to excellent yields.

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Section: Methodsmentioning

confidence: 99%

An Expedient and Stereoselective Synthesis of Alkenyl Nonaflates from Silyl Enol Ethers: Optimization, Scope and Limitations

2002

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“…29), as shown in Scheme 17. 97 In contrast, the same reaction carried out by using the corresponding vinyl triflate gave cyclododecyne in 95% yield. 97…”

Section: Reactions Of Sp 2 -Phosphates 31 Reactions Of Vinyl (Enol)-p...mentioning

confidence: 98%

Phosphate esters as “tunable” reagents in organic synthesis

Protti

Fagnoni

2008

Chem. Commun.

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The essential role phosphates have in biochemistry has no parallel in man-made chemistry, where the poor reactivity of these esters towards nucleophilic substitution makes more reactive substrates such as halides and sulfonates preferred. Nevertheless, phosphates are acquiring an increasing role in organic synthesis as long as new activation modes become available. These include metal catalysis and photochemistry (the latter effective with benzyl and aryl derivatives) that may turn the present limitation into a promising opportunity by devising convenient tunable reactions.

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“…[7] For example, Brummond and co-workers have reported an interesting protocol involving kinetic deprotonation of ketones followed by phosphorylation. [8] The resulting enol phosphates 6 were converted to disubstituted allenes 7 by treatment with LDA (Scheme 3). Impressive selectivity was observed for the desired allene products over alkynes.…”

Section: Scheme 2 Competing Pathways For Proton Eliminationmentioning

confidence: 99%

Synthesis of Allenes by 1,2-Elimination

Armstrong

2020

COC

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Allenes represent an extremely important class of organic molecules, which, as a result of their twisted orthogonal π-systems can possess axial chirality. A wide array of methods for allene synthesis have been reported, such as the substitution of propargylic electrophiles, isomerization of alkynes and sigmatropic rearrangement. An alternative approach for the synthesis of allenes is 1,2-elimination of an appropriately substituted precursor. This mini-review highlights recent examples of 1,2-elimination processes, which target allenes including both polar and radical processes. The main focus is upon how control over the stereospecificity (e.g. syn- or anti-) of the 1,2-elimination process can enable the synthesis of enantioenriched axially chiral allenes. Recent developments in this field are presented including both enantiospecific and catalytic asymmetric methods.

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Strategy for the Preparation of Allenes from α,β-Unsaturated and Saturated Ketones via Enol Phosphates

Cited by 46 publications

References 7 publications

An Expedient and Stereoselective Synthesis of Alkenyl Nonaflates from Silyl Enol Ethers: Optimization, Scope and Limitations

An Expedient and Stereoselective Synthesis of Alkenyl Nonaflates from Silyl Enol Ethers: Optimization, Scope and Limitations

Phosphate esters as “tunable” reagents in organic synthesis

Synthesis of Allenes by 1,2-Elimination

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