Rapid Stereospecific Methylation of Alcohols and Glycols with Sodium Hydride/Methyl Iodide<sup>1</sup>

Arylselenenyl fluorides ArSeF are obtained from diselenides Ar2Se2 or arylselenotrimethylsilanes ArSe-SiMe3, and XeF2. They are detected by low-temperature 19F and 77Se NMR spectroscopy. Substitution in the ortho position of the aromatic ring to provide electronic or steric protection is a requirement for their formation. ArSe--F compounds decompose according to 3 ArSe-F-->[ArSe-SeF2Ar]+ArSe-F-->ArSeF3+Ar2Se2. Reaction energies for this disproportionation as well as that of the sulfur and tellurium homologues have been calculated with MP2, CCSD(T,) and B3 LYP methods. They were found to be increasingly exothermic in the sequence S

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“…For compound 2: Methylation of o-bromobenzyl alcohol (ACROS) in THF with MeI/NaH [65] yielded o-methoxymethyl bromobenzene. B.p.…”

Section: Precursors Of Diselenidesmentioning

confidence: 99%

“…102 8C/13 mbar; 13 59, 132.43, 128.50, 127.50, 127.39, 122.01 (C arom ), 73.89 (OCH), 30.52 (CH 2 ), 10.02 ppm (CH 3 ). Etherification of (S)-o-(1-hydroxy-1-propyl)bromobenzene with MeI/ NaH [65] in THF led to (S)-o-(1-methoxy-1-propyl)bromobenzene. B.p.…”

Section: Precursors Of Diselenidesmentioning

confidence: 99%

First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar₂Se₂/XeF₂ and ArSeSiMe₃/XeF₂ Reagents

Poleschner

Seppelt

2004

Chemistry A European J

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“…The aqueous phase was acidified and extracted with ether. The organic extracts were dried, and solvent was removed to yield 104 mg of a white solid, mp 80-82.5', 21: ir (KBr) 3470 (m), 1690 cm-l (5). A portion of the crude 21 (86 mg, 0.38 mmol) was esterified with diazomethane to yield 106 mg of an oil which was used without further purification: ir 3585 (m), 3410 (br), 1740 cm-l (s).…”

Section: Methodsmentioning

confidence: 99%

Photochemical formation of 12-methylene-cis-bicyclo[8.2.0]dodecan-1-ol from 2-methylenecyclododecanone. Restricted rotation in a biradical intermediate

Hemperly¹,

Wolff²,

Agosta³

1975

J. Org. Chem.

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Irradiation of 2-methylenecyclododecanone (3) leads to 12-methylene-cis-bicyclo[8.2.0]dodecan-l-01 (11) in 87% yield, unaccompanied by the cyclobutyl or cyclopropyl ketones usually formed photochemically from CYmethylene ketones. Pyrolysis of 11 leads to enone 15 and bicyclic ketone 14, which is the cyclobutyl ketone anomalously absent from irradiation of 3. The structures of 11,14, and 15 are supported by spectroscopic and chemical data. Restricted rotation about the C(a)-C(P) bond in biradical intermediate 13 is advanced as an explanation for the exceptional behavior of 3. These results suggest the importance of conformational mobility of a short-lived biradical in determining the products formed on photolysis of a-methylene ketones.Photochemical isomerization of a variety of a-methylene ketones leads to cyclobutyl ketones, accompanied in some cases by related cyclopropyl ketones and methylenecyclobutano1s.l Equation 1 gives a typical example in which all three types of products are found. There is good evidencethat the cyclopropyl and cyclobutyl ketones arise by way of biradical intermediates in which 0 hydrogen (1, for cyclopropyl ketones) or y hydrogen (2, for cyclobutyl ketones) has been abstracted by the carbonyl oxygen.2 It is quite likely that the methylenecyclobutanols also arise by way of biradical intermediates (as 2),' although there is no direct evidence for this, and the possibility remains open that these alcohols represent a concerted [ , , 2 + ,2] cycloaddition3 of the y carbon-hydrogen bond with the carbonyl group. The major photoproduct is cyclobutyl ketone in most cases, and frequently no methylenecyclobutanol is found a t all. An exception to this generalization is the photolysis of 2-methylenecyclododecanone (3), which furnishes solely a single isomer of the related methylenecyclobutanol 4 in high yield (eq 2).l Ketone 3 is the only medium-or large-ring compound investigated, and its exceptional photochemical behavior presumably is related to this structural feature. Our purpose in the present study was to investigate this isomerization of 3 in more detail; in this connection we have determined the stereochemistry of 4 and carried out sensitization and quenching experiments on its formation from 3. In addition we have studied the thermolysis of 4 and succeeded thereby in preparing the cyclobutyl ketone which is anomalously absent in photolysis of 3. The results are discussed in detail below; they permit us to offer a reasonable explanation for the behavior of 3 in terms of restricted rotation in a biradical intermediate, thus providing an instructive example of conformational control over the fate of a short-lived intermediate.The convenient availability of both isomers of bicyclo-[8.2.0]dodecan-l-o1, 5 and 6, from photolysis of cyclododecanone4 suggested that a simple proof of the stereochemistry of 4 would involve its correlation with one of these known alcohols. This approach was successful in demonstrating a cis ring fusion in 4, and the structural formulas showing the degradation ...

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“…[α] D 20 = Ϫ0.6 (neat, for 78.8% ee); lit. : 26 [α] D 27 = Ϫ0.59 (neat). IR (CHCl 3 ): 3603s, 2953s, C NMR (CDCl 3 , 100 MHz): 72.9 (s), 41.6 (t), 39.6 (t), 34.2 (t), 27.9 (d ), 26.3 (q), 22.6 (q), 12.6 (t), 8.1 (q).…”

Section: Synthesis Of 37-dimethyl-3-octyl Derivativesmentioning

confidence: 99%

Solvent effects on the steric course of the solvolysis of tertiary acyclic derivatives

Müller

Rossier

2000

J. Chem. Soc., Perkin Trans. 2

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Rapid Stereospecific Methylation of Alcohols and Glycols with Sodium Hydride/Methyl Iodide¹

Cited by 48 publications

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First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar₂Se₂/XeF₂ and ArSeSiMe₃/XeF₂ Reagents

First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar₂Se₂/XeF₂ and ArSeSiMe₃/XeF₂ Reagents

Photochemical formation of 12-methylene-cis-bicyclo[8.2.0]dodecan-1-ol from 2-methylenecyclododecanone. Restricted rotation in a biradical intermediate

Solvent effects on the steric course of the solvolysis of tertiary acyclic derivatives

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Rapid Stereospecific Methylation of Alcohols and Glycols with Sodium Hydride/Methyl Iodide1

Cited by 48 publications

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First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar2Se2/XeF2 and ArSeSiMe3/XeF2 Reagents

First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar2Se2/XeF2 and ArSeSiMe3/XeF2 Reagents

Photochemical formation of 12-methylene-cis-bicyclo[8.2.0]dodecan-1-ol from 2-methylenecyclododecanone. Restricted rotation in a biradical intermediate

Solvent effects on the steric course of the solvolysis of tertiary acyclic derivatives

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Rapid Stereospecific Methylation of Alcohols and Glycols with Sodium Hydride/Methyl Iodide¹

First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar₂Se₂/XeF₂ and ArSeSiMe₃/XeF₂ Reagents

First Detection of a Selenenyl Fluoride ArSeF by NMR Spectroscopy: The Nature of Ar₂Se₂/XeF₂ and ArSeSiMe₃/XeF₂ Reagents