Synthetic methods. VIII. Hydroxylation of carbonyl compounds via silyl enol ethers

Häßner, Alfred; Reuss, Robert H.; Pinnick, Harold W.

doi:10.1021/jo00911a027

Cited by 156 publications

(56 citation statements)

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“…The first route is the formation of epoxide 8 (Scheme 3, stages iii), the second is the Baeyer-Villiger reaction with formation of lactone 9 and subsequent acid hydrolysis to 3a (Scheme 3, stage v). Epoxide 8 is similar in structure to the products of oxidation of the enol-ethers observed in other works [24][25][26][27]. These products can be transformed by hydrolysis into 2-hydroxycycloalkanones under conditions of acid catalysis.…”

Section: R Can Be = H Me Hc=o O=c (H) Osupporting

confidence: 66%

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New transformation of cycloalkanone acetals by peracids α,ω-dicarboxylic acids synthesis

Terent’ev

Chodykin

2005

Open Chemistry

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Section: R Can Be = H Me Hc=o O=c (H) Osupporting

confidence: 66%

“…The data from works [24][25][26][27] in which the stage of enol-ether epoxidation was studied and the fact that 2a is formed upon oxidation of 6 (Table 2) allows one to assume that the formation of epoxide 8 is an initial stage of oxidative transformation of 6 from 2a (Scheme 3, stage i).…”

Section: R Can Be = H Me Hc=o O=c (H) Omentioning

confidence: 99%

New transformation of cycloalkanone acetals by peracids α,ω-dicarboxylic acids synthesis

Terent’ev

Chodykin

2005

Open Chemistry

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“…The rearrangement of α-hydroxyaldehydes into α-ketols has since been shown to be a general problem in attempts to prepare α-hydroxyaldehydes in both acidic (28) and basic media (29). Hassner et al (29) noted that α-hydroxyaldehydes may not only rearrange to α-ketols but may also dimerize or polymerize.…”

Section: Synthesis Of α-Ketols 15a-kmentioning

confidence: 99%

“…Hassner et al (29) noted that α-hydroxyaldehydes may not only rearrange to α-ketols but may also dimerize or polymerize. In that regard, Schulz and coworkers found that attempts to convert their thianthreniumyl adducts (5) into α-hydroxyaldehydes with bases such as NaOH, NaHCO 3 , and Na 2 CO 3 in aqueous solution failed, and only oligomeric and polymeric products were obtained.…”

Section: Synthesis Of α-Ketols 15a-kmentioning

confidence: 99%

Reactions of thianthrene cation radical tetrafluoroborate with aldehydes: formation of α-(5-thianthreniumyl)aldehyde tetrafluoroborates – a facile synthesis of α-ketols through Lobry de Bruyn–van Ekenstein rearrangement

Rangappa

Shine

2008

Journal of Sulfur Chemistry

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Reactions of thianthrene cation radical tetrafluoroborate (Th namely, butanal, pentanal, hexanal, heptanal, octanal, nononal, decanal, undecanal, dodecanal, tridecanal, and 3-phenylpropanal, led to the formation of α-(5-thianthreniumyl)aldehyde tetrafluoroborates (13a-k). Adducts (13a-k) are unstable and are converted to the corresponding hydrates (14a-k) when exposed to moisture or by deliberate addition of water to their solutions. Adducts (13a-k) and their hydrates (14a-k) were characterized with 1 H, 13 C, and DEPT NMR spectroscopy. Interestingly, when solutions of adducts (13a-k) in acetonitrile were stirred with activated alumina, facile conversion to α-ketols (15a-k) occurred. It is proposed that the formation of α-ketols (15a-k) occurred through the Lobry de Bruyn-van Ekenstein rearrangement from the initially formed α-hydroxyaldehydes. α-Ketols 15a-j were isolated in good yield and their identities were confirmed with NMR spectroscopy.

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“…Similarly, the 4OMs/10OMs acetolysis rate ratio is evaluated to be 10 -8. 9 . 29 Again, we are unable to obtain any supporting evidence for rate acceleration of 4OMs in relatively low nucleophilicity solvents.…”

Section: −10mentioning

confidence: 99%

Solvent Effects and Steric Course in the Solvolysis of 1,3,3-Trimethyl-2-oxocyclopentyl Mesylate in Comparison with 1,1,3,3-Tetramethyl-2-oxobutyl System

Takeuchi¹,

Ushino²,

Okazaki³

et al. 2001

Bulletin of the Chemical Society of Japan

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The rates of solvolysis in various solvents were determined for 1,1,3,3-tetramethyl-2-oxobutyl tosylate ( 1 OTs) and 1,3,3-trimethyl-2-oxocyclopentyl mesylate ( 4 OMs). The rate data for 1 OTs reinforced that the linear Grunwald − Winstein (GW) relationship of 1 OMs previously reported by Creary for non-aqueous solvents must also hold for aqueous organic solvents. 4 OMs showed a markedly dispersed GW relationship that is, on the other hand, well correlated with an extended GW equation involving a nucleophilicity parameter. Such solvent dependence, such marked effects of added sodium azide on rates, and the 100% inversion of configuration of the solvolysis product showed that the solvolysis of 4 OMs would be categorized to S N 2(intermediate), whereas 1 OMs and 1 OTs solvolyze via limiting S N 1. The negligible susceptibility of 1 OTs toward nucleophilicity of solvent and azide probe indicates that the nucleofuge leaves along the C=O axis in such a manner that the back-strain (B-strain) in the ground state is efficiently relieved in the transition state. Comparison of solvolysis rates of 1 OMs and 4 OMs with those of the corresponding parent substrates suggests that the transition states of these substrates would not be stabilized by carbonyl π conjugation. The origin of the unexpectedly fast rates of solvolysis of 1 OMs has been discussed. #The chemistry of carbocations that are destabilized by a strongly electron-withdrawing substituent has been a subject of considerable interest for the past two decades in the field of physical organic chemistry.1 Some carbocations having a carbonyl or a cyano substituent on the α carbon have been spectroscopically observed under stable ion conditions. 1e The α -carbonyl cation stabilized by p -methoxyphenyl substituents has even been isolated.2 These works appear to have brought about an impression that the α -carbonyl cations were much more stable than had been thought before. 3##The solvolyses of various α -carbonyl substrates have been extensively carried out by Creary and co-workers.1c-e They demonstrated that many α -carbonyl cations can be relatively easily formed as solvolysis intermediates: for example, 1,1,3,3-tetramethyl-2-oxobutyl methanesulfonate (mesylate) ( 1 OMs ) solvolyzes 55 times faster than isopropyl mesylate ( 2 OMs) in 97% 1,1,1,3,3,3-hexafluoro-2-propanol containing 3% water (97HFIP).4 Since 1 OMs had been postulated to solvolyze 10 4 − 10 5 times as slow as 2 OMs, the enormous amount of acceleration was ascribed to possible contribution of the carbonyl substituent to stabilize the incipient cation by the mesomeric (+M) effect 5 3a ↔ 3b (Chart 1). 1,4Previously, we have suggested that the mesomeric stabilization as described by 3a ↔ 3b would be improbable by comparing the solvolysis rates of various 2-oxo bridgehead compounds. 6 We herein report the full account of a previous communication 7 on the solvolysis of 1,3,3-trimethyl-2-oxocy-

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Synthetic methods. VIII. Hydroxylation of carbonyl compounds via silyl enol ethers

Cited by 156 publications

References 1 publication

New transformation of cycloalkanone acetals by peracids α,ω-dicarboxylic acids synthesis

New transformation of cycloalkanone acetals by peracids α,ω-dicarboxylic acids synthesis

Reactions of thianthrene cation radical tetrafluoroborate with aldehydes: formation of α-(5-thianthreniumyl)aldehyde tetrafluoroborates – a facile synthesis of α-ketols through Lobry de Bruyn–van Ekenstein rearrangement

Solvent Effects and Steric Course in the Solvolysis of 1,3,3-Trimethyl-2-oxocyclopentyl Mesylate in Comparison with 1,1,3,3-Tetramethyl-2-oxobutyl System

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