Stereoselectivity in the boron trifluoride catalyzed rearrangement of a 1,1-disubstituted ethylene oxide

Blackett, B. N.; Coxon, James M.; Hartshorn, Michael P.; Richards, Kenneth Edward

doi:10.1021/ja00711a074

Cited by 25 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reactivity of Meinwald rearrangement reactions can be affected by other side reactions. Thus, the low yield obtained for the 2- tert -butyl-2-methyloxirane + BF 3 reaction is due to the significant formation of an acetal by the reaction between the original epoxide and the ketone resulting from the Meinwald rearrangement …”

Section: Discussionmentioning

confidence: 99%

Theoretical Study on the BF₃-Catalyzed Meinwald Rearrangement Reaction

2014

View full text Add to dashboard Cite

The mechanisms of the BF3-catalyzed Meinwald rearrangement reactions of five epoxides in dichloromethane solution have been studied at the M062X/6-311++G(2df,2pd) level. Accordingly, the Lewis acid-epoxide complex can react through several alternative pathways, though three phases (ring opening, C-C bond rotation, and hydrogen or alkyl group migration) are required in any path. In some cases, a concerted pathway (involving all three successive phases) is found. Otherwise, the reaction takes place through a reaction mechanism involving a zwitterion or a BF3 addition compound (formed by fluoride transfer from the BF3 moiety to the incipient carbocationic center generated by C-O bond rupture) or both as reaction intermediate(s). The BF2-bound fluorohydrin yields the reaction product through a concerted process involving fluoride transfer from the C-F bond to the OBF2 group and hydrogen or alkyl group migration, as first demonstrated in this work. Effects of a number of features (solvent effects, concurrent hydrogen/alkyl group migration, carbocation substitution, benzylic conjugation) are also discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

Theoretical Study on the BF₃-Catalyzed Meinwald Rearrangement Reaction

2014

View full text Add to dashboard Cite

show abstract

“…btdee is currently used in many chemical reactions, such as the ring opening of epoxides. It is currently accepted that ring opening by an alcohol, for instance, is facilitated by the attachment of the BF 3 Lewis acid to the oxygen atom in the epoxide; one of the carbons is then attacked by the entering group . The exact mechanism in nonprotonogenic solvents has not been thoroughly investigated however.…”

Section: Introductionmentioning

confidence: 99%

“…It is currently accepted that ring opening by an alcohol, for instance, is facilitated by the attachment of the BF 3 Lewis acid to the oxygen atom in the epoxide; one of the carbons is then attacked by the entering group. 1 The exact mechanism in nonprotonogenic solvents has not been thoroughly investigated however. In our own experiments on the epoxide ring opening of (1R,2R,3R,4S)-1,2-oxi-3,4-O-isopropyliden-5-chloro-5-cyclohexen-2,3-diol reported elsewhere, 2 we have found the counterintuitive result that BF 3catalyzed ring opening in dichloromethane was achieved more easily by 3-chlorobenzoic acid than by 4-methoxybenzyl alcohol.…”

Section: Introductionmentioning

confidence: 99%

A New Perspective in the Lewis Acid Catalyzed Ring Opening of Epoxides. Theoretical Study of Some Complexes of Methanol, Acetic Acid, Dimethyl Ether, Diethyl Ether, and Ethylene Oxide with Boron Trifluoride

et al. 2006

View full text Add to dashboard Cite

Several 1:1, 1:2, and 2:2 complexes between BF3 and CH3OH (Met), CH3COOH (AcA), (CH3)2O (DME), (CH3CH2)2O (DEE), and (CH2)2O (EOX) have been studied using ab initio (MP2) and density functional theory (DFT) (PBE, B3LYP) methods and the 6-311++G(3df,2pd) basis set. Geometrical structures and vibrational frequencies are reported, in most cases, for the first time. A detailed comparison of the vibrational frequencies for the O...BF3 vibrational modes, as well as for the nu(OH) band in the methanol and acetic acid complexes with BF3, is performed, and the theoretical frequency shifts are compared with the available experimental information. Thermochemical properties are calculated by employing counterpoise correction to alleviate the basis set superposition error. The DFT enthalpy of complexation of the 1:1 complexes results in the order of stability (AcA)2>AcA:BF3>DEE:BF3>DME:BF3>Met:BF3>EOX:BF3>(Met)2; in contrast, MP2 shows the noticeable difference that the AcA:BF3 complex is much less stable (similar to Met:BF3). The order of stability shows that, even though acetic acid prefers dimerization to complexation with BF3, the case is exactly the opposite for methanol. In both cases, the interaction of BF3 with the dimer gives rise to very stable trimers. However, in contrast to the interaction of BF3 with the methanol dimer being stronger than that with the monomer, the interaction of BF3 with the acetic acid dimer is weaker than that with the monomer. The relative strength of the complexes, discussed in the context of BF3-catalyzed ring opening of epoxides, suggests that the effect of the catalyst in a nonprotogenic solvent should be more properly ascribed to activation of the nucleophile instead of activation of the epoxide.

show abstract

“…Some years ago, we established that in the acid-catalyzed rearrangement of an unsymmetrical 1,1-disubstituted epoxide to aldehyde there was marked stereoselection in the 1,2-hydride shift of one of the prochiral hydrogens. This stereoselection was first observed for the boron trifluoride-catalyzed rearrangement of 2,3,3-trimethyl-1,2-epoxybutane and is now known to be general . For epoxide 1 and 2 , the ratio of deuteride/hydride migration, that is, 3 / 4 , was 2.65:1 (standard deviation 0.08) and 0.89:1 (standard deviation 0.03), respectively (Figure ).…”

Section: Introductionmentioning

confidence: 63%

“…For epoxide 1 and 2 , the ratio of deuteride/hydride migration, that is, 3 / 4 , was 2.65:1 (standard deviation 0.08) and 0.89:1 (standard deviation 0.03), respectively (Figure ). After taking into account the inherent kinetic preference for hydride to migrate in preference to deuteride, the experiment shows that there is therefore a marked inherent preference for the migration of the group, hydrogen or deuterium, cis to the methyl group …”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Study of the Mechanism of the BF₃-Catalyzed Rearrangement of 2,3,3-Trimethyl-1,2-epoxybutane to 2,3,3-Trimethylbutanal

Coxon

Thorpe

2000

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

The potential energy surface for the rearrangement of BF(3)-coordinated 2,3,3-trimethyl-1,2-epoxybutane to 2,3, 3-trimethylbutanal has been investigated at the B3LYP/6-31G level of theory. SCRF(SCI-PCM) solvent calculations and theoretical primary and secondary kinetic isotope effects at the same level of theory provide support for a two-step process with ring opening of the BF(3)-coordinated epoxide to a tertiary carbocation intermediate followed by hydride/deuteride migration to give aldehyde. The experimentally measured primary isotope effect (k(H)(D)/k(D)(H)) requires a correction for an appropriate secondary isotope effect to give a true isotope effect k(H)(H)/k(D)(H). For the lowest energy pathway for hydride migration, the calculated secondary kinetic isotope effect is 0.92, which when applied to the experimentally measured isotope effect of k(H)(D)/k(D)(H) = 1.73 gives a revised "true" primary kinetic isotope effect of k(H)(H)/k(D)(H) = 1.59. This compares with a calculated value of 2.01. From intermediate 15, migration of the C1-H(a) proton via 19 is energetically favored over C1-H(b) migration via 18 and this result is consistent with the experimental results in which hydride migration of the proton cis to the methyl is favored.

show abstract

Stereoselectivity in the boron trifluoride catalyzed rearrangement of a 1,1-disubstituted ethylene oxide

Cited by 25 publications

References 0 publications

Theoretical Study on the BF₃-Catalyzed Meinwald Rearrangement Reaction

Theoretical Study on the BF₃-Catalyzed Meinwald Rearrangement Reaction

A New Perspective in the Lewis Acid Catalyzed Ring Opening of Epoxides. Theoretical Study of Some Complexes of Methanol, Acetic Acid, Dimethyl Ether, Diethyl Ether, and Ethylene Oxide with Boron Trifluoride

Density Functional Theory Study of the Mechanism of the BF₃-Catalyzed Rearrangement of 2,3,3-Trimethyl-1,2-epoxybutane to 2,3,3-Trimethylbutanal

Contact Info

Product

Resources

About

Stereoselectivity in the boron trifluoride catalyzed rearrangement of a 1,1-disubstituted ethylene oxide

Cited by 25 publications

References 0 publications

Theoretical Study on the BF3-Catalyzed Meinwald Rearrangement Reaction

Theoretical Study on the BF3-Catalyzed Meinwald Rearrangement Reaction

A New Perspective in the Lewis Acid Catalyzed Ring Opening of Epoxides. Theoretical Study of Some Complexes of Methanol, Acetic Acid, Dimethyl Ether, Diethyl Ether, and Ethylene Oxide with Boron Trifluoride

Density Functional Theory Study of the Mechanism of the BF3-Catalyzed Rearrangement of 2,3,3-Trimethyl-1,2-epoxybutane to 2,3,3-Trimethylbutanal

Contact Info

Product

Resources

About

Theoretical Study on the BF₃-Catalyzed Meinwald Rearrangement Reaction

Theoretical Study on the BF₃-Catalyzed Meinwald Rearrangement Reaction

Density Functional Theory Study of the Mechanism of the BF₃-Catalyzed Rearrangement of 2,3,3-Trimethyl-1,2-epoxybutane to 2,3,3-Trimethylbutanal