The stereochemistry of reductive dehalogenation

Williamson, Kenneth L.; Hsu, Ya-Han; Young, E.I.

doi:10.1016/s0040-4020(01)90984-6

Cited by 29 publications

(9 citation statements)

References 28 publications

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“…We have recently shown that 7,7-dichlorobicycloheptenes are stereoselectively reduced to 7-5yn-chloro compounds by zinc and acetic acid or chromous acetate. 20 The reduction of 1521 with zinc dust in refluxing acetic acid gave 11 in 55% yield, further confirming our structure assignments.…”

Section: Resultssupporting

confidence: 78%

“…The 7-syn-chloro-enqfo-acetoxy configuration of 20b was further confirmed by zinc/acetic acid reduction of the corresponding hexachloro compound, the complete details of which have recently been published. 20 The isomer ratios for 18a, b, c determined by both glpc and integration of the nmr spectrum of the crude reaction mixture agreed very well (see Table I), thus indicating that the adducts are stable at the rather high temperature of the gas chromatograph and further demonstrating that these are the products of a kinetically controlled reaction. The styrene adducts were prepared at three different temperatures.…”

Section: Resultsmentioning

confidence: 67%

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Stereochemistry of the Diels-Alder reaction. syn-anti Isomerism

Williamson¹,

Hsu²,

Lacko³

et al. 1969

J. Am. Chem. Soc.

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Electronic and steric factors governing syn-anti isomerism in the Diels-Alder reaction have been investigated employing 1,2,3,4,5-pentachlorocyclopentadiene as the plane asymmetric dienophile. The predominance of ti«?/-7-chloro isomers in many cases has been ascribed to forces arising from dipole-dipole, dipole-induced dipole, and London-dispersion interactions, the predominance of endo over exo isomers to secondary orbital interactions and the lack of anti-exo isomers to steric hinderance in the transition state.heptatriene9 and cyclooctatetraene10 gives 1 and 2, respectively. On the other hand 5-acetoxy-1,3 -cyclopen-1 (syn) 2 (syn)3 (anti)tadiene with ethylene gives 311 in which the dienophile(1) Presented in part at the 155th National Meeting of the American Chemical Society, San Francisco, Calif., April 1-5, 1968, and the Halocarbon Conference held at the Eastern Research Laboratory of the Dow Chemical Co., Wayland, Mass., May 5-8, 1968.(2) Taken from the thesis of Mrs. Hsu submitted to Mount Holyoke College in partial fulfillment of the requirements for the Ph.D. degree.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 67%

Stereochemistry of the Diels-Alder reaction. syn-anti Isomerism

Williamson¹,

Hsu²,

Lacko³

et al. 1969

J. Am. Chem. Soc.

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“…Proton NMR spectroscopy provided corroborating evidence as to the extent and location of dechlorination (see Supporting Information for detailed descriptions). According to NMR spectroscopy studies on dechlorinated analogues of dieldrin, 50 isodrin, 51 and 1,2,3,4,7,7hexachloro-5-endo-acetoxy-bicyclo[2.2.1]-2-heptene, 52 which all contain the HCCP moiety, a proton in an endo position has a slightly higher chemical shift than a proton in an exo position of a chlorinated ring in an otherwise identical structure. The same trend is observed in the case of dechlorinated DP products (Table 1).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Dechlorinated Analogues of Dechlorane Plus

Brazeau¹,

Pena-Abaurrea

Shen

et al. 2018

Environ. Sci. Technol.

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Degradation products of the chlorinated additive flame retardant Dechlorane Plus (DP) have been discovered globally. However, the identity of many of these species remains unknown due to a lack of available analytical standards, hindering the ability to quantitatively measure the amounts of these compounds in the environment. In the present study, synthetic routes to possible dechlorinated DP derivatives were investigated in an effort to identify the environmentally significant degradation products. The methano-bridge chlorines of anti- and syn-DP were selectively replaced by hydrogen atoms to give six new hydrodechlorinated DP analogues. The identity and absolute configuration of all of these compounds were confirmed by GC-MS, NMR spectroscopy, and X-ray diffraction studies. These compounds were observed in sediment samples from streams and rivers in relatively rural areas of Ontario and are thus environmentally relevant.

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“…A sharp singlet at 4.33 for the proton at C-9 shows the absence of coupling of this proton with any other protons in the molecule. In the alternative structure (10) with -chloro orientation, the long-range coplanar W coupling with endoprotons at C-2 and C-5 with the proton at C-9 would have split this signal as observed in similar anticompounds by Williamson et al (1968).…”

Section: Resultsmentioning

confidence: 98%

Superoxide-mediated monodehalogenation of cyclodiene insecticides

Dureja¹,

Walia²,

Mukerjee³

1984

J. Agric. Food Chem.

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Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable. From a dissertation by R.L.R. "Distribution and metabolism of cis-and trons-resmethrin [(5-benzyl-3-furyl)methyl 2,2-dimethyl-3-(2methyl-l-propenyl)cyclopropanecarboxylate] in lactating cattle",

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The stereochemistry of reductive dehalogenation

Cited by 29 publications

References 28 publications

Stereochemistry of the Diels-Alder reaction. syn-anti Isomerism

Stereochemistry of the Diels-Alder reaction. syn-anti Isomerism

Dechlorinated Analogues of Dechlorane Plus

Superoxide-mediated monodehalogenation of cyclodiene insecticides

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