Acid-catalyzed ring expansion of 1-(1-methoxy-1,2-propadienyl)-2-cyclobuten-1-ols. Synthesis of 5-hydroxy-5-vinyl-2-cyclopenten-1-ones and their stereoselective transformation to 5-(2-acetoxyethylidene)-2-cyclopenten-1-ones

Stone, Guy B.; Liebeskind, L. S.

doi:10.1021/jo00302a027

Cited by 42 publications

(5 citation statements)

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“…Analogously, the ethoxy-substituted cyclobutanol derivative 229 , under the action of zinc bromide underwent ring enlargement and subsequent elimination to the corresponding cyclopentenone 230 in 45% yield. These products were used as starting materials for allyl esters which, upon palladium-catalyzed substitution gave 5-alkylidene-2-cyclopentenones as substructures of naturally occurring bioactive compounds 80 …”

Section: Five-membered Ringsmentioning

confidence: 99%

“…These products were used as starting materials for allyl esters which, upon palladium-catalyzed substitution gave 5-alkylidene-2-cyclopentenones as substructures of naturally occurring bioactive compounds. 110 Moore and Liebeskind et al discovered independently that 4-alkenyl/aryl-cyclobutenones can be ring expanded to aromatic systems. Moore et al used 2-dienyl-4-oxycyclobutenones as starting materials for the synthesis of annelated furans and monocyclic lactones.…”

Section: Five-membered Ringsmentioning

confidence: 99%

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The Application of Cyclobutane Derivatives in Organic Synthesis

2003

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Section: Five-membered Ringsmentioning

confidence: 99%

Section: Five-membered Ringsmentioning

confidence: 99%

The Application of Cyclobutane Derivatives in Organic Synthesis

2003

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“…In the experiment involving ethoxyacetylene, 40 (36%) is formed as abundantly as 35 . In light of the very general nature of cyclobutenol ring expansions, this hydroxy ketone might well arise by means of the illustrated electronic reorganization.…”

Section: Resultsmentioning

confidence: 99%

The Squarate Ester−Polyquinane Connection. An Analysis of the Capacity of Achiral Divinyl Adducts To Rearrange Spontaneously to Polycyclic Networks Housing Multiple Stereogenic Centers

Paquette

Morwick

1997

J. Am. Chem. Soc.

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The condensation of diisopropyl squarate and related cyclobutene-1,2-diones with 2 equiv of the same alkenyl anion or 1 equiv each of two different alkenyl anions can be a very effective method for the highly stereocontrolled synthesis of di-, tri-, and tetraquinanes. Two reaction cascades have been identified. The most prevalent and often exclusive reaction course is triggered by trans 1,2-addition of the two nucleophiles. Two consecutive conrotatory processes subsequently arise to deliver a doubly charged eight-membered ring intermediate, protonation of which leads to transannular adolization. The second option begins with cis 1,2-addition, this event triggering structural reorganization via a dianionic oxy-Cope rearrangement. When the alkenyl anions are sufficiently substituted, the two pathways are distinguishable on stereochemical grounds. A minor pathway consisting of trans 1,4-addition is seen to operate in certain contexts, especially when the alkenyllithium is "soft". Acetylide anions can also be utilized successfully; in such cases, the benefit of regiocontrolled protonation surfaces and gives rise to a single product. Other aspects of these complex tandem reactions have been investigated and are discussed. X

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“…Materials. 3-Methoxycyclobutenone, 3-ethoxycyclobutenone, 3-( N , N -dimethylamino)cyclobutenone,3a 4a,b , and 4c 3a were synthesized according to the literature. IR matrix isolation data for these compounds have been described 3a…”

Section: Experimental and Computational Sectionmentioning

confidence: 99%

Retro-Ene Reactions in Acylallene Derivatives

1998

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Allenic esters and amides 4 undergo a retro-ene reaction to vinylketene (6) and an aldehyde or imine (5) under the conditions of flash vacuum thermolysis (FVT). The same products are obtained by FVT of cyclobutenones 7 via electrocyclic ring opening to alkoxy- or aminovinylketenes 3 and 1,3-rearrangement of ketenes 3 to allenes 4. All the intermediates and products were characterized by matrix isolation IR spectroscopy, and in the case of 4c the reaction was also monitored by online mass spectrometry. A lower temperature for the retro-ene reaction of 4c, eliminating an imine, than for 4a, eliminating formaldehyde, is in agreement with a lower calculated activation barrier (167 and 181 kJ mol(-1), respectively, at the G2(MP2,SVP) level of theory). The allenic amide 11 undergoes an analogous retro-ene reaction to the (unobserved) vinylketene 13, the latter isomerizing to cyclohexenylacrolein 16 in a 1,5-H shift (calculated barrier 125 kJ mol(-1); G2 (MP2, SVP)).

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Acid-catalyzed ring expansion of 1-(1-methoxy-1,2-propadienyl)-2-cyclobuten-1-ols. Synthesis of 5-hydroxy-5-vinyl-2-cyclopenten-1-ones and their stereoselective transformation to 5-(2-acetoxyethylidene)-2-cyclopenten-1-ones

Cited by 42 publications

References 0 publications

The Application of Cyclobutane Derivatives in Organic Synthesis

The Application of Cyclobutane Derivatives in Organic Synthesis

The Squarate Ester−Polyquinane Connection. An Analysis of the Capacity of Achiral Divinyl Adducts To Rearrange Spontaneously to Polycyclic Networks Housing Multiple Stereogenic Centers

Retro-Ene Reactions in Acylallene Derivatives

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