The ortho-Claisen Rearrangement. V. The Products of Rearrangement of Allyl m-X-Phenyl Ethers<sup>1</sup>

White, William N.; Slater, Carl

doi:10.1021/jo01068a004

Cited by 32 publications

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“…Organic solvents were dried by standard methods and distilled under nitrogen before use. All reagents were obtained from commercial suppliers and used without further purification with the exception of [{Ru(h 3 :h 3 -C 10 H 16 )A C H T U N G T R E N N U N G (m-Cl)Cl} 2 ] (1), [37] allyl 2-chlorophenyl ether (3 b), [38] allyl 3-chlorophenyl ether (3 c), [39] allyl 4-chlorophenyl ether (3 d), [40] allyl 4-formylphenyl ether (3 e), [41] 4-(N-acetylamino)phenyl allyl ether (3 f), [40] allyl 2-methylphenyl ether (3 g), [42] allyl 4-methylphenyl ether (3H), [42] 6-allyloxyquinoline (3 k), [43] 2,2'-bisA C H T U N G T R E N N U N G (allyloxy)-1,1'-binaphthalene (3 l), [44] 2-acetylphenyl allyl ether (3 m), [45] 2-allyloxybenzophenone (3 n), [46] 2-cyanophenyl allyl ether (3 o), [47] allyl ethyl ether (3 p), [48] 3-(allyloxypropyl)benzene (3 s), [49] and allyl diphenylmethyl ether (3 t), [50] which were prepared by following the methods reported in the literature. GC measurements were made with a Hewlett-Packard HP6890 Preparation of allyl 3-(diethylamino)phenyl ether (3 j): K 2 CO 3 (11.0 g, 80 mmol) was added to a stirred solution of 3-(diethylamino)phenol (3.41 g, 20 mmol) in acetone (100 mL) at room temperature, and the resulting mixture heated to reflux for 1 h. Allyl bromide (1.76 mL, 22 mmol) was then added, and reflux continued for additional 4 h. After this time, the reaction mixture was cooled to room temperature, filtered, and the filtrate evaporated to dryness.…”

Section: Entrymentioning

confidence: 99%

Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study

Varela‐Álvarez

Sordo

Piedra

et al. 2011

Chemistry A European J

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A general mechanism to rationalize Ru(IV) -catalyzed isomerization of the C=C bond in O-allylic substrates is proposed. Calculations supporting the proposed mechanism were performed at the MPWB1K/6-311+G(d,p)+SDD level of theory. All experimental observations in different solvents (water and THF) and under different pH conditions (neutral and basic) can be interpreted in terms of the new mechanism. Theoretical analysis of the transformation from precatalyst to catalyst led to structural identification of the active species in different media. The experimentally observed induction period is related to the magnitudes of the energy barriers computed for that process. The theoretical energy profile for the catalytic cycle requires application of relatively high temperatures, as is experimentally observed. Participation of a water molecule in the reaction coordinate is mechanistically essential when the reaction is carried out in aqueous medium. The new mechanistic proposal helped to develop a new experimental procedure for isomerization of allyl ethers to 1-propenyl ethers under neutral aqueous conditions. This process is an unique example of efficient and selective catalytic isomerization of allyl ethers in aqueous medium.

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Section: Entrymentioning

confidence: 99%

Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study

Varela‐Álvarez

Sordo

Piedra

et al. 2011

Chemistry A European J

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“…[11] This highly impacted the designing of aqueous organic reactions by the use of synergetic and potential catalysts and promoters. [12] One of the methods for allylation of alkyl/ aryl/ hetero arylated compounds containing -OH, -NH & -CH groups is with allyl halides in the presence of K 2 CO 3 , [13] tetra (n-butyl) ammonium hydroxide, [14] NaOH, [15] gallium, [16] Cs 2 CO 3 , [17] NaH, [18] compounds remains as a major goal.…”

Section: Introductionmentioning

confidence: 99%

Sodium Perborate: A Facile Catalyst for Allylation of Active Centers

Jayaprakash

Krishna

Prasad

et al. 2014

Synthetic Communications

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An efficient and eco-friendly allylation of O-H, N-H and C-H groups has been achieved successfully with the reaction of allyl bromide by using sodium perborate as a new catalyst in aqueous media. The advantage of this method is operationally simple, short reaction time, high yield and simple work-up conditions over the previously reported conventional methods such as amination, oxyalkylation reactions of allyl bromide and Friedel-Crafts allylation chemistry.

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“…A similar preference for rearrangement "towards" the meta-substituent is observed in the normal aromatic Claisen rearrangement (see Section 1.2.3, Regiochemistry), except rearrangement predominantly occurs "away" in the case of the methoxy-substituent. [28][29] Site selectivity in fused aromatic systems such as 18m has been previously noted. 18b Computational investigations of these unexpected regiochemical results will be presented in Chapter 3.6.…”

Section: Scheme 29mentioning

confidence: 73%

“…White and Slater, 28 in their investigation on the topic, noted that in all cases except for the electrondonating methoxy-substituent, rearrangement occurs primarily "towards" the substituted metaposition (Scheme 1.17). The authors did not suggest an explanation for this selectivity.…”

Section: Regiochemistrymentioning

confidence: 99%

“…Despite their homology, such a consistent regioselectivity is not present in the usual aromatic Claisen rearrangement (see section 1.2.3). White and Slater, 28 for instance, observed preferential formation of 1,2,4 substituted products from 3-methoxyphenyl allyl ethers (rearrangement "away from" the meta substituent) but a bias for 1,2,3 product generation in 3-bromophenyl allyl ethers (rearrangement "towards" the meta substituent, see Section 1.2.3, Scheme 1.17). Marsaioli et al 29 later correlated this behaviour to preferences in the ground-state conformation leading to the regioisomeric products, and not the difference in the energies of the competing transition-state barriers.…”

Section: Regioselectivitymentioning

confidence: 99%

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Experimental and Computational Investigations into the Benzyl-Claisen Rearrangement

Burns¹

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Being a prime example of a [3,3]-sigmatropic process, the Claisen rearrangement is an essential reaction at the core of modern organic chemistry. Its undisputed value is derived not only from its reliable and predictable application to the synthesis of complex molecules but, also, in being a reaction of longstanding interest in the field of computational organic chemistry, contributing to our theoretical understanding of pericyclic reactions. A long-standing shortcoming of the Claisen rearrangement is that while allyl-vinyl and allyl-phenyl ethers are viable substrates for the reaction, applications to benzyl-vinyl ethers have rarely been reported. To date, a very limited number of benzylic substrates have been investigated, with the few successful reactions typically requiring harsh conditions. Herein, we report the optimisation of a procedure for Claisen rearrangements of benzylvinyl ethers (referred to here as the "Benzyl-Claisen" rearrangement) based on a previous literature procedure and, for the first time, investigate the scope of such a process. Benzyl ketene acetals were generated in a short two-step procedure by bromoacetalisation of the requisite benzyl alcohol followed by elimination of HBr. Heating the ketene acetals in refluxing DMF smoothly converted the substrates to the product tolylacetates, which were saponified and isolated as their carboxylic acid derivatives. In the course of the reaction optimisation, a pronounced solvent effect was observed: DMF led to the [3,3]-rearranged product, whereas conducting the reaction in xylene led to a mixture of radical dissociation-recombination products. Electron-donating and electron-neutral substituents (-Me, -Ph, -Cl, -Br, -OMe and -SMe) gave the highest yields in the Benzyl-Claisen rearrangement (24-50%) whereas substrates derived from electron-poor aromatic systems (-NO 2 , -CN, -COOBn, -SO 2 Me or -CF 3 ) tended to decompose under the reaction conditions. Claisen rearrangements conducted on meta-substituted systems were observed, unexpectedly, to preferentially generate products via rearrangement "towards" the meta substituent, leading to sterically crowded 1,2,3-trisubstituted tolylacetates. iii The mechanism of the Benzyl-Claisen rearrangement was investigated using computational methods. The activation free energy for rearrangement of benzyl vinyl ether calculated with the high-accuracy CBS-QB3 method was 40.1 kcal/mol, which is 10.2 kcal/mol higher than that of the aliphatic Claisen rearrangement of allyl vinyl ether at the same level of theory. The C-2 alkoxy substituent on the ketene acetal was shown to be essential in making the process both thermodynamically and kinetically favourable, lowering the barrier by 10.2 kcal/mol and stabilising the intermediate isotoluene by 18.0 kcal/mol. As a general rule, substitution of the aromatic systems with an electron-donor group was calculated to lower the barrier for the reaction whilst electronwithdrawing substituents were calculated to raise it. The para-OMe substituent was calculated to lower...

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The ortho-Claisen Rearrangement. V. The Products of Rearrangement of Allyl m-X-Phenyl Ethers¹

Cited by 32 publications

References 0 publications

Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study

Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study

Sodium Perborate: A Facile Catalyst for Allylation of Active Centers

Experimental and Computational Investigations into the Benzyl-Claisen Rearrangement

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The ortho-Claisen Rearrangement. V. The Products of Rearrangement of Allyl m-X-Phenyl Ethers1

Cited by 32 publications

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Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study

Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study

Sodium Perborate: A Facile Catalyst for Allylation of Active Centers

Experimental and Computational Investigations into the Benzyl-Claisen Rearrangement

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The ortho-Claisen Rearrangement. V. The Products of Rearrangement of Allyl m-X-Phenyl Ethers¹