Desiccant efficiency in solvent drying. 3. Dipolar aprotic solvents

Burfield, David R.; Smithers, Roger H.

doi:10.1021/jo00414a038

Cited by 177 publications

(87 citation statements)

References 5 publications

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“…Acetone (Me 2 CO) was stirred over B 2 O 3 for at least 24 h, distilled, and finally degassed by purging with Argon. [60] Literature known procedures were employed to synthesize the macrocyclic amine side-arm, 1,4-diisopropyl-1,4,7-triazacyclononane, [61,62] and the bridging unit, 3,5-bis(chlorocarbonyl)-1H-pyrazole, [63] used to prepare HL Am .…”

Section: General Materials and Methodsmentioning

confidence: 99%

Improved Synthesis and Detailed Characterization of a Hybrid Pyrazole‐TACN Dinucleating Ligand

Dalle

Dechert

Meyer

2015

Zeitschrift anorg allge chemie

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Abstract. An improved synthetic procedure is reported for the hybrid ligand HL, composed of two TACN macrocycles bridged by a central pyrazole moiety. Detailed NMR spectroscopic characterization showed that asymmetry in this dinucleating organic scaffold can be induced at room temperature through the use of anhydrous conditions, owing to pyrazole-NH prototropy. Thermally induced line broadening allowed for an estimation of the thermodynamic parameters for this proton exchange reaction, giving ΔH ‡ = 46.

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Section: General Materials and Methodsmentioning

confidence: 99%

Improved Synthesis and Detailed Characterization of a Hybrid Pyrazole‐TACN Dinucleating Ligand

Dalle

Dechert

Meyer

2015

Zeitschrift anorg allge chemie

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“…(CD3)2S0 (Merck) was dried with 4A molecular sieves as recommended by Burfield and Smithers (35). All other solvents were obtained from commercial sources and purified as described previously (14).…”

Section: Methodsmentioning

confidence: 99%

Reactions of the ambident super-electrophile series: the 2-(nitroaryl)-4,6-dinitrobenzotriazole 1-oxides with isopropoxide ion. Pathways of decomposition of the anionic σ-adducts

Dust¹,

Buncel²

1994

Can. J. Chem.

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This paper is dedicated to Professors David B. McLeatz and Ian D. Spenser JULIAN M. DUST and ERWIN BUNCEL. Can. J. Chem. 72,218 (1994). To elucidate the reactivity of super-electrophiles such as 4,6-dinitrobenzofuroxan as compared to normal electrophiles such as 1,3,5-trinitrobenzene, reaction of isopropoxide ion (iPrO-) with a series of ambident super-electrophiles was studied by 400 MHz 'H nuclear magnetic resonance spectroscopy. The 2-(nitroary1)-4,6-dinitrobenzotriazole l-oxides, 1-3, possess both a super-electrophilic (C-7) site and a normal electrophilic (C-1') site. Nucleophiles can demonstrate selectivity for attack at C-7, which leads to formation of persistent anionic u-adducts (Meisenheimer complexes), as compared to C-1', which leads to N-2:C-1' bond scission. The most reactive substrate, 2-(2',4',6'-trinitrophenyl)-4,6-dinitrobenzotriazole l-oxide (Pi-DNBT, 1) was found to be the least selective substrate in C-7 adduct formation, while 2-(2',4'-dinitrophenyl). and 2-(4'-nitropheny1)-4,6-dinitrobenzotriazole l-oxides (DNP-DNBT, 2, and NP-DNBT, 3, respectively) showed increasing selectivity towards iPrC-, in turn. These results are discussed on the basis of overall selectivity for C-7 adduct formation and the relative selectivity of iPrO-as compared to methoxide and tert-butoxide ions. The conclusions are illustrated using comparative energy profiles. In terms of pathways for decomposition of the adducts, the C-7 adducts decompose via dissociation back to substrate and nucleophile and, thence, through C-1' adduct formation to the scission products. However, for 1, the C-7 adduct l a has now been found to decompose to 7-isopropyl-2-picryldinitrobenzotriazole, lc. The possible mechanism of this formal internal redox will be discussed. Chem. 72,218 (1994). Afin d'tvaluer la rCactivitC des super-Clectrophiles, comme le 4,6-dinitrobenzofuroxane, par rapport a celle d'tlectrophiles normaux, comme le 1.3,s-trinitrobenz&ne, on a utiliser la resonance magnCtique nuclkaire du 'H ? I 400 MHz pour ttudier la rCaction de l'ion isopropylate (iPrC-) avec une sCrie de superClectrophiles ambidents. Les 2-(nitrowl)-4,6-dinitrobenzotriazole l-oxydes, 1-3, posskdent un site superClectrophile (C-7) ainsi qu'un site Clectrophile normal (C-l').Les nucltophiles permettent de dtmontrer une sClectivitC pour l'attaque en C-7 qui conduit a la formation d'adduits u anioniques persistants (complexes de Meisenheimer) alors que I'attaque en C-l'conduit a une scission de la liaison N-2:C-1' . On a trouvC que le substrat le plus rkactif, la 2-(2',4',6'-trinitrophCnyl)-4,6-dinitrobenzotriazole I-oxyde (Pi-DNBT, I), est le substrat le moins stlectif pour la formation d'un adduit en C-7 alors que les 2-(2',4'-dinitrophCny1)-et 2-(4'-nitrophCny1)-4,6-dinitrobenzotriazole l-oxydes (respectivement la DNP-DNBT, 2, et NP-DNBT, 3) prCsentent chacune une sClectivitC de plus en plus grande vis-a-vis du iPrO-. On discute de ces rksultats en fonction de la sClectivitC globale de la formation d'adduits en C-7 et la sClectivitC relative du iPrO-comp...

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“…DMF was dried by heatingfor4 hat 90°C with calcium hydride followed by distillation under reduced pressure, or by stirring over phosphorous pentoxide for 1 week, followed by decanting and distillation under reduced pressure . Until use DMF was stored over activated 3 A molecular sieve (29). LH20 Gel was prepared and used according to the manufacturer's (Pharmacia) instructions.…”

Section: Methodsmentioning

confidence: 99%

Chlorosulphation of amino sugars: synthesis of methyl 2-acetamido-4-amino-2,4,6-trideoxy-β-D-glucopyranoside (bacillosamine) from a D-glucosamine derivative

Bundle¹,

Josephson²

1980

Can. J. Chem.

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This paper is dedicated to Prof. Raymond U . Lemieux on the occasion of his 60th birthday DAVID R. BUNDLE and STAFFAN JOSEPHSON. Can. J. Chem. 58,2679 (1980). Chlorosulphation of methyl 2-deoxy-2-phthalimido-P-D-glucopyranoside 3 under controlled conditions provided either methyl 6-chloro-2,6-dideoxy-2-phthalimido-~~-glucopyranoside 4 or methyl 4,6dichloro-2,4,6trideoxy-2-phthalimido-~-~-galactopyranoside 5. Chlorination at C-4 occurs to the exclusion of that at C-3, in sharp contrast to the chlorosulphation of methyl P-D-glucopyranoside which is known to give both the 4,6-dichloro-galacto-and 3,6dichloro-allo-pyranosides. Conversion of the chlorinated phthalimido derivatives 4and 5 to the corresponding 2-acetamido-2-deoxyhexopyranosides 6 and 7 permitted reduction of the chloro functions by palladium, W-4 m n e y nickel, and nickel boride. Reduction of methyl 2-acetamido-6-chloro-2,6-dideoxy-P-D-glucopyranoside 6 by Raney nickel gave methyl 2-acetamido-2,6-dideoxy-P-D-glucopyranoside 8. Selective dechlorination at C-4 was achieved by palladium catalysed reduction of methyl 2-acetamido-4,6-dichloro-2,4,6-trideoxy-~-~-galactopyranoside 7. Nickel boride or Raney nickel reduction of 7 effected selective dechlorination at C-6 to give methyl 2-acetamido-4-chloro-2,4,6-trideoxy-P-D-galactopyranoside 9. Azide displacement of the 4-chloro group of 9 provided a simple route to the 2,4-diamino sugar bacillosamine. A side product of the azide displacement reaction was the unsaturated sugar, methyl 2-acetamido-2,4,6trideoxy-a-L-threo-hex-4-enopyranoside, 14.

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Desiccant efficiency in solvent drying. 3. Dipolar aprotic solvents

Cited by 177 publications

References 5 publications

Improved Synthesis and Detailed Characterization of a Hybrid Pyrazole‐TACN Dinucleating Ligand

Improved Synthesis and Detailed Characterization of a Hybrid Pyrazole‐TACN Dinucleating Ligand

Reactions of the ambident super-electrophile series: the 2-(nitroaryl)-4,6-dinitrobenzotriazole 1-oxides with isopropoxide ion. Pathways of decomposition of the anionic σ-adducts

Chlorosulphation of amino sugars: synthesis of methyl 2-acetamido-4-amino-2,4,6-trideoxy-β-D-glucopyranoside (bacillosamine) from a D-glucosamine derivative

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