Neighboring‐Group Effects and Rearrangements in Reactions of Cyclopropylmethyl, Cyclobutyl, and Homoallyl Systems

Hanack, Michael; Schneider, H.‐J.

doi:10.1002/anie.196706661

Cited by 58 publications

(8 citation statements)

References 96 publications

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“…So2volysis. The behaviour of 2-methyl-3-bromonortricyclene (111) with aqueous silver ion was entirely as expected and was exactly that exhibited by the nor compound, namely, generation of the extremely stable cyclopropylcarbinyl cation with no evidence of ring opening on reaction with solvent [Za] [14].…”

mentioning

confidence: 73%

Reaction of 2‐Methylnorborn‐2‐ene with N‐Bromosuccinimide [1]

Jefford

Wojnarowski

1970

Helvetica Chimica Acta

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The reaction of 2-methylnorborn-2-ene with N-bromosuccinimide produced exo-3bromo-2-methylenenorbornane and 2-methyl-3-bromonortricyclene in a 3 : 1 ratio. No 2-bromomethyl-norborn-2-ene was found. Most of the unreacted olefin was found to be isomerized to 2methylenenorbornane.The hydrolysis of 2-methyl-3-bromo-nortricyclene with silver acetate in a 50 yo mixture of acetone and water afforded the corresponding alcohol and acetate. Exo-3-bromo-2-methylenenorbornane on similar treatment gave the exo-3-hydroxy-2-methylene-norbornane and 2-hydroxymethyl-norbornane and 2-hydroxymethyl-norborn-2-ene and their corresponding acetates in a 3: 2 ratio.An ionic rather than a radical mechanism is proposed for the bromination reaction. In the solvolysis reactions of the resulting bromides the nature of the ionic intermediates is discussed.Introduction, -The behaviour of N-bromosuccinimide (NBS) as a brominating agent towards bridged bicyclic olefins is capricious. When the allylic C-H bond lies in the nodal plane of the double bond, reactivity is usually directed towards the homoallylic position or the double bond itself [Z]. When an allylic position is available, bromination is thought to proceed via allylic radicals which subsequently give the corresponding endocyclic allylic bromides (31.As 2-methylnorborn-2-ene contains both these structural elements, its reactivity is of crucial interest. Furthermore, the properties of the bromides obtained relate to the problem of the nature of bridged cations.Results. -2-Methylnorborn-2-ene (I) and N-bromosuccinimide were allowed to react in boiling carbontetrachloride containing benzoyl peroxide. The resulting products were identified as exo-3-bromo-2-methylene-norbornane (II), 3-bromo-%methylnortricyclene (111) and 2-methylenenorbornane (IV). The structures of I1 and 111 were assigned from a consideration of their NMR. and IR. spectra. The exo assignment of the bromine at C-3 in I1 was made on the basis of the magnitude of the coupling constant exhibited for C-3-H, (3J N 1.8 Hz) ; a larger value (ca. 4 Hz) would l) Address inquiries to the

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confidence: 73%

Reaction of 2‐Methylnorborn‐2‐ene with N‐Bromosuccinimide [1]

Jefford

Wojnarowski

1970

Helvetica Chimica Acta

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“…However, deamination of cyclohex-3-enyl amine and solvolysis cyclohex-3-enyl tosylate gives exo-and endo-bicyclo[3.1.0]hex-2-yl derivatives as 6-43% of the products resulting from nucleophilic capture (101,103,104). The modest yield of bicyclic products in these reactions apparently is the result of competing nucleophilic capture prior to cyclization and hydride shift to the 2-cyclohexenyl cation.…”

Section: Methodsmentioning

confidence: 99%

“…Although the homoallylic-+cyclopropylcarbinyl cyclization is wellprecedented in carbonium ion chemistry (101,102) there seem to be no reports of the direct cyclization of the tertiary 4-terpineny1 carbonium ion. However, deamination of cyclohex-3-enyl amine and solvolysis cyclohex-3-enyl tosylate gives exo-and endo-bicyclo[3.1.0]hex-2-yl derivatives as 6-43% of the products resulting from nucleophilic capture (101,103,104).…”

Section: Methodsmentioning

confidence: 99%

Biogenetic-Type Rearrangements of Terpenes

Coates

1976

Fortschritte Der Chemie Organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products

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“…The mixture was stirred at room temperature for 10 min. After work-up (see 14) and removal of the solvent on a rotary evaporator 1.95 g (82%) of a pale yellow liquid was obtained which was shown to be practically pure by NMR: NMR (CCI4) 1.10-1.90 (m, 4 ), 3.80 (s, 3 ), 6.70-7.75 (q, 4 H); MS M+ m/e (rel intensity) 240 (10), 238 (12), and 135 (100).…”

Section: Methodsmentioning

confidence: 99%