Cyclopropyldiazomethane

Moss, Robert A.; Shulman, Franklyn C.

doi:10.1039/c19660000372

Cited by 4 publications

(3 citation statements)

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“…Solvents were dried and purified by conventional methods prior to use; diethyl ether and THF were freshly distilled from sodium/benzophenone. Caution: The generation and handling of diazomethane requires special precaution . Flash-column chromatography: Merck silica gel 60, 0.040−0.063 mm (230−400 mesh).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Enantiomerically Pure Cyclopropanes from Cyclopropylboronic Acids

1999

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A general method for the stereocontrolled synthesis of cyclopropanes is described. Various, highly stable, enantiomerically pure alkenylboronic esters 13 have been conveniently synthesized by the direct hydroboration of alkynes 11 using the new chiral 1,3,2-dioxaborolane 15. The high stability was also demonstrated by the selective deprotection of a tert-butyldimethylsilyl protecting group without hydrolyzing the boronic ester. The diastereoselective cyclopropanation of the olefins was achieved by the palladium(II) acetate catalyzed decomposition of diazomethane. This process was optimized giving cyclopropylboronic esters 20/21 in high yield (89-99%) and with good to excellent diastereomeric ratios (up to 95:5). The diastereomers were separated by means of MPLC and their configurations determined by X-ray crystallography (compound 21c), by transformation to known cyclopropanols, and by correlation of NMR data. Treatment with LiAlH(4) followed by acidic hydrolysis yielded the enantiomerically pure cyclopropylboronic acid 27 for the first time and allowed the nearly quantitative recovery of the chiral auxiliary 3. Different protocols for the Suzuki coupling reaction of compound 27 were investigated.

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Section: Methodsmentioning

confidence: 99%

Synthesis of Enantiomerically Pure Cyclopropanes from Cyclopropylboronic Acids

1999

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“…Anions play important roles in area of medicine and catalysis. Pollutant anions have been linked to eutrophication of rivers 5 and to carcinogenesis 6, since it can disrupt hormones production needed for normal health 7. Nevertheless, the design of anion receptors is particularly challenging due to the larger ion radius relatively to cations, by the more complex electrostatic binding interactions, the higher sensitivity to pH variations and the wider range of geometries that requires complementary receptors adjusted to the anionic guest 8.…”

Section: Introductionmentioning

confidence: 99%

Study of a Novel Bisnaphthalimidopropyl Polyamine as Electroactive Material for Perchlorate‐selective Potentiometric Sensors

et al. 2015

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In this work, the new polyamine bisnaphthalimidopropyl‐4,4’‐diaminodiphenylmethane is proposed as a new ionophore for perchlorate potentiometric sensors. The optimal formulation for the membrane comprised of 12 mmol kg−1 of the ionophore, and 68 % (w/w) of 2‐nitrophenyl phenyl ether as plasticizer and 31 % (w/w) of high molecular weight PVC. The sensors were soaked in water for a week to allow leakage of anionic impurities and for one day in a perchlorate solution (10−4 mol L−1) to improve reproducibility due to its first usage. The stability constant for the ionophore‐perchlorate association in the membrane, log βIL1=3.18±0.04, ensured a performance characterized by the slope of 54.1 (±0.7) mV dec−1 to perchlorate solutions with concentrations between 1.24×10−7 and 1.00×10−3 mol L−1. The sensors are insensitive to pH between 3.5 to 11.0, they have a practical detection limit of 7.66 (±0.42) ×10−8 mol L−1 and a response time below 60 s for solutions with perchlorate concentrations above 5×10−6 mol L−1. The accuracy of the results was confirmed by the analysis of the contaminant in a certified reference water sample.

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“…One example of chemical factor is the concept of Sabatier [ 11 which can be used as a selection method [2]. The physical factor is represented by the metastable state which implies the dispersion andlor the disorder (amorphous state or crystal defects) of the active mateofrial 131.…”

Section: Introductionmentioning

confidence: 99%

Thermal deactivation of heterogeneous catalyst, part 1. The theta‐rule ‐ a critical review

Kral

1988

Chem Eng & Technol

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Thermal deactivation can be described either by deactivation kinetics or by the isokinetic effect. The latter expression is used synonymously with the "compensation effect" and the "ThetaRule". An examination of the original literature shows that only the compensation effect is applicable to thermal deactivation but not the Theta-Rule. The introduction of the preparation temperature as a parameter of the compensation effect results in a "modified Theta-Rule", which describes the experimental data and is proposed for the non-separable kinetics. The consequence of the observed deviations from the validity range of the Theta-Rule is that the activation energy cannot be used as a universal activity criterion.

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Cyclopropyldiazomethane

Abstract: CYCLOPROPYLDIAZOMETHANE (I) has been cited asprepared and subjected to the requisite reaction an intermediate in various carbenic and cationic conditions, all postulates of its intermediacy lack decompositions.1 However, until (I) has been total cogency. Attempted preparations of (I)

Cited by 4 publications

References 0 publications

Synthesis of Enantiomerically Pure Cyclopropanes from Cyclopropylboronic Acids

Synthesis of Enantiomerically Pure Cyclopropanes from Cyclopropylboronic Acids

Study of a Novel Bisnaphthalimidopropyl Polyamine as Electroactive Material for Perchlorate‐selective Potentiometric Sensors

Thermal deactivation of heterogeneous catalyst, part 1. The theta‐rule ‐ a critical review

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