Pericyclic Reactions of Cumulenes* *This chapter is dedicated to Professor R. B. Woodward on the occasion of his 60th birthday.

Ghosez, Léon; O’Donnell, Martin J.

doi:10.1016/b978-0-12-470502-9.50008-0

Cited by 35 publications

(10 citation statements)

References 208 publications

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“…-The Bredt olefins 1-3 and the l-methylcyclooctenes 4 and 11 react with diphenylketene (6) to give a single cycloadduct. This result fits nicely into the great number of experimental observations collected for the [2 + 21-cycloaddition reaction of ketenes to olefins [9]. The complete syn-stereo~electivity~) reveals that, although the olefinic double bond is distorted, it still undergoes clean suprafacial addition to ketenes.…”

supporting

confidence: 76%

“…This reaction is considered to occur via a concerted [n 2 s + 71 2 a]-cycloaddition, in which the ketene double bond constitutes the antarafacial reaction partner [9]. The frontier orbital approach has been applied successfully to the problem of regioselectivity of this cycloaddition [lo].…”

mentioning

confidence: 99%

“…( 9 ) 0 . 2 7 6 ( 9 ) -0.046 ( 9 ) 0.249 ( 9 ) 0.080 ( 9 ) 0.292 ( 9 ) -0 . 0 6 7 ( 9 ) 0.02019) 0 .…”

unclassified

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[2 + 2]‐Cycloadditions to Strained Bridgehead Olefins. II. Diphenylketene

Becker

Hohermuth

Rihs

1982

Helvetica Chimica Acta

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SummaryThe strained bridgehead olefins bicyclo [3.3. llnon-1-ene (l), bicyclo [4.2. Ilnon-1 (8)-ene (2), and bicyclo [4.2. llnon-1-ene (3), and the comparable monocyclic (E)-1-methylcyclooctene (4) react with diphenylketene (6) to give a single cycloadduct 7, 8, 9 and 10, respectively, in which the diphenyl-substituted C-atom is bound to the bridgehead. The structure of the cyclobutanone 8 has been determined by X-ray analysis of a twin crystal obtained by crystallization with spontaneous enrichment of enantiomers.

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supporting

confidence: 76%

mentioning

confidence: 99%

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[2 + 2]‐Cycloadditions to Strained Bridgehead Olefins. II. Diphenylketene

Becker

Hohermuth

Rihs

1982

Helvetica Chimica Acta

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“…The formation and reactions of vinylketenes have been previously reviewed both specifically, 2-4,29,29a and within reviews of other ketenes. 6,7,30 This chapter will discuss all cycloaddition and electrocyclization reactions of vinylketenes, allenylketenes, and alkynylketenes. The Tabular Survey includes all such reactions of vinylketenes known to the authors through July 2013.…”

Section: Methodsmentioning

confidence: 99%

“…Ketene cycloadditions have been extensively reviewed 1,3,4,7,29,30,32 and will not be considered in detail in this chapter. Ketene [2+2] cycloadditions, including those of vinylketenes, are generally agreed to involve an initial orthogonal arrangement of the two reactants, with the smaller ketene substituent (R S ) closest to the alkene (Scheme 11).…”

Section: Theory Of Ketene Cycloadditions and Electrocyclizationsmentioning

confidence: 99%

Cycloaddition and Electrocyclic Reactions of Vinylketenes, Allenylketenes, and Alkynylketenes

Tidwell

2015

Organic Reactions

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Vinylketenes may be prepared by the typical procedures used for other ketenes, and are usually highly reactive, except when bulky groups and silyl substituents are present. They are extensively utilized in cycloaddition reactions and electrocyclizations, including dimerizations, inter‐ and intramolecular reactions with alkenes, alkynes, imines, and carbonyl groups, and intramolecular reactions with aryl and heteroaryl groups. These pericyclic reactions are widely used in syntheses of carbocyclic and heterocyclic products, and are particularly useful for the preparation of β‐lactams and β‐lactones. Allenylketenes and alkynylketenes also undergo cycloaddition and electrocyclic reactions.

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Enantioselective Vicinal Bis-Acylation of Olefins

et al. 2002

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A two‐step sequence for the asymmetric vicinal acylation of olefins by a [2+2+1] strategy is reported. The key reaction is a [2+2] cycloaddition of an olefin to a chiral keteniminium salt derived from N‐tosylsarcosinamide. This is followed by a regioselective Baeyer–Villiger oxidation of the resulting cyclobutanone to yield a lactol derivative that is equivalent to the product of addition of a carboxyl and a carbonyl group to the olefin. N‐Tosylsarcosinamides derived from prolinol methyl ether and 2,5‐dimethylpyrrolidine gave the best yields and diastereoselectivities. Five‐ and six‐membered cycloolefins only gave cis products as expected. With seven‐ and eight‐membered rings and cis 1,2‐disubstituted acyclic olefins, partial or complete epimerisation of the cis to the trans adducts was observed. Facial selectivities were generally good except for terminal olefins. The oxidation step proceeded in high yields to give crystalline compounds which could usually be obtained in enantiopure form by simple recrystallisation.

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Pericyclic Reactions of Cumulenes* *This chapter is dedicated to Professor R. B. Woodward on the occasion of his 60th birthday.

Cited by 35 publications

References 208 publications

[2 + 2]‐Cycloadditions to Strained Bridgehead Olefins. II. Diphenylketene

[2 + 2]‐Cycloadditions to Strained Bridgehead Olefins. II. Diphenylketene

Cycloaddition and Electrocyclic Reactions of Vinylketenes, Allenylketenes, and Alkynylketenes

Enantioselective Vicinal Bis-Acylation of Olefins

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