Methods for the Preparation of Bridgehead Olefins

Keese, Reinhart

doi:10.1002/anie.197505281

Cited by 82 publications

(13 citation statements)

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“…The nitrogen atom of DMAP coordinates to Si2 atom with the Si2 À N1 distance of 1.8764(14) Å, which is moderately longer than the typical Si À N distance (1.71-1.74 Å) 27 . The Si1 atom has no substituent and the Si1 À Si3 distance is 2.6215(6) Å, which is considerably longer than those of known tetrasilabicyclo[1.1.0]butanes (2.367-2.412 Å) 28,29 , but still shorter than the longest Si À Si distance reported so far (2.697 Å for (t-Bu) 3 SiSi(t-Bu) 3 ) 30 . The endocyclic Si1-Si2 and ARTICLE Si2-Si3 bond distances, 2.2906(6) and 2.2556(6) Å, respectively, are between the typical Si À Si (ca.…”

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confidence: 63%

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A heavy analogue of the smallest bridgehead alkene stabilized by a base

2014

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Bicyclo[1.1.0]but-1(2)-ene (BBE), one of the smallest bridgehead alkenes and C 4 H 4 isomers, exists theoretically as a reactive intermediate, but has not been observed experimentally. Here we successfully synthesize the silicon analogue of BBE, tetrasilabicyclo[1.1.0]but-1(2)-ene (Si 4 BBE), in a base-stabilized form. The results of X-ray diffraction analysis and theoretical study indicate that Si 4 BBE predominantly exists as a zwitterionic structure involving a tetrasilahomocyclopropenylium cation and a silyl anion rather than a bicyclic structure with a localized highly strained double bond. The reaction of base-stabilized Si 4 BBE with triphenylborane affords the [2 þ 2] cycloadduct of Si 4 BBE and the dimer of an isomer of Si 4 BBE, tetrasilabicyclo[1.1.0]butan-2-ylidene (Si 4 BBY). The facile isomerization between Si 4 BBE and Si 4 BBY is supported by theoretical calculations and trapping reactions. Structure and properties of a heavy analogue of the smallest bridgehead alkene are disclosed.

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confidence: 63%

“…Their syntheses, highly strained structures and high reactivities have widely attracted the attention of both theoretical and experimental chemists since the pioneering work of Bredt [1][2][3][4][5] . Bicyclo[1.1.0]but-1(2)-ene (BBE, E ¼ C, Fig.…”

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confidence: 99%

A heavy analogue of the smallest bridgehead alkene stabilized by a base

2014

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“…According to Bredt's rule, amines with nitrogen in a bridgehead position cannot form a C¼N bond [37,38], which means that these types of molecules will act by physical quenching. Hydrogen peroxide can initiate the oxidation of polyolefins, so this mechanism does not lead to stabilization.…”

Section: Quenching By Aminesmentioning

confidence: 99%

Photostabilisation of Polymer Materials

Gijsman

2010

Photochemistry and Photophysics of Polymer Materials

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“…The generally applied synthetic methods for bridgehead olefins [8] did not seem appropriate for the preparation of bicyclo [5.1.1]non-l (8)-ene (5). The reductive elimination of a 1,2-dihalide or a related compound would necessitate a lengthy synthesis of a substituted bicyclo [5.1. ljnonane.…”

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The Intramolecular Ramberg‐Bäcklund Reaction: A Convenient Method for the Synthesis of Strained Bridgehead Olefins

Becker

Labhart

1983

Helvetica Chimica Acta

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A c T A -V O I .~~, Fas.4(1983)-Nr. 109 I002 HI.LV~I.ICA CHIMICA ACTA -Vol. 66, Fasc. 4 ( I 9833 -Nr. 109 11 Scheme 3 12 13 14 Scheme 4 15 13 16 the hexahydroindenes 13 and 16 by the intermediacy of the a-chlorosulfone 14 and the corresponding a , a-dichlorosulfone [17].In spite of the discouraging examples above, chances are still intact that base treatment of an a-bromo-(ora-chloro-)sulfone 17 may lead to 5 by Ramberg-Bucklund reaction. It is true that the a-H-, S-and Br-atoms cannot adopt a favorable W-type arrangement in any conformation of the isomers of 17, but on the other hand, competing 1,2-elimination of HBr is also disfavored because the P-H-atom at the bridgehead and the Br-atom bisect under a dihedral angle of 20-40", or 80loo", respectively (estimated from molecular models). In addition, the unsaturated sulfone 18 with a bridgehead double bond is likewise strained, although considerably less than the Bredt olefin 5. 18Intramolecular Ramberg-Backlund reaction of 2-bromo-l-thiadecalin-1, l-di-oxide3). -In order to shed more light on the question of competing Ramberg-Bucklund reaction and 1,2-elimination in a-halosulfones and to solve some confusing inconsistencies found by Kattenberg et al. with the decalin-type sulfones 11, 15 and related compounds [ 161 [ 171, the preparation and base treatment of 2-bromo-

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Methods for the Preparation of Bridgehead Olefins

Cited by 82 publications

References 112 publications

A heavy analogue of the smallest bridgehead alkene stabilized by a base

A heavy analogue of the smallest bridgehead alkene stabilized by a base

Photostabilisation of Polymer Materials

The Intramolecular Ramberg‐Bäcklund Reaction: A Convenient Method for the Synthesis of Strained Bridgehead Olefins

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