Potassium-18-Crown

Toluene, potassium, 18-crown-6, 100% yield.Tetrahydrofuran can also be used as the solvent in this process. ... 

Photoswitching has allowed Kawashima et al. to control the configuration of the N-N double bond and the coordination number of potassium 18-crown-6 2-(phenylazo)phenyltetrafluorosilicates 836 and 837, which are accessible by the reaction of 2-(phenylazo)phenyltrifluorosilane 838 with KF/18-crown-6 (Scheme 116).830 In the (Z)-form, the silicon atom of 837 is pentacoordinated, whereas in the (E)-form, one nitrogen atom of the azo group of 836 intramoleculary coordinates to the silicon atom, thus extending its coordination sphere to six ligands. Almost... 

Tetraalkylammonium stannates 30c and 39a obtained in CH2C12 or CH3CN solution in 62-71% yield are susceptible to hydrolysis. The more stable potassium 18-crown-6 stannates 30d, 39b and 40, handled for a prolonged time in air, were prepared in quantitative yields in toluene solution. 

Cleavage of -lactones.1 The blue solution of potassium-18-crown-6 in THF cleaves (3-propiolactone at -20° to furnish a dianion (1) which on protonation gives methyl acetate. A similar reaction of the (3-lactone 2 can be used to obtain isopropyl propionate (3). 

The Potassium complex of I8-Crown-6 or Potassium Naph-thalenide effects ring-opening to give acetates or their alkylated derivatives in good yield (eq 3). Treatment of the reaction mixture obtained from p-methyl-p-propiolactone and potassium-18-crown-6 with hydrochloric acid or alkyl halides gives the acetate (S) or its alkylated derivative (6), respectively. The a,3-unsaturated carboxylic acid (7) or its ester (8) is formed by the action of the potassium naphthalenide-18-crown-6 complex. ... 

Pictet-Spengler cyclization, 161 Pinacol rearrangements, 51 B-(3>a-Pinanyl-9-borabicyclo[3.3.1 ]-nonane, 320-321 Piperidine, 183 Piperidine enamines, 16 Piperidines, 18 Piperonal, 232 Piperylene, 372 N-Pivaloylaniline, 69 Platinum catalysts, 321 Podophyllotoxin, 165 Polygodial, 167 Polymethoxyarenes, 368 Polymethylpyrimidines, 345 Polynucleotides, 88 Polyphosphate ester, 437 Polyphosphoric acid, 321-322 Potassioacetone, 73 Potassium-Alumina, 322 Potassium bis(trimcthylsilyl)amide, 38 Potassium f-butoxide, 323 Potassium carbonate, 323 Potassium-18-Crown-6, 322 Potassium cyanide, 324 Potassium cyclopentadienide, 111 Potassium 2,6-di-f-butyl-4-methylphen-oxide, 48... 

ALCOHOLS Chlorotrimethylsilane-Sodium iodide. Iron carbonyl. Phenyl chlorothionocarbonate. Potassium-18-Crown-6. Tri-n-butyltin hydride. CARBONYL COMPOUNDS Bis(ben-zoyloxy)borane. Bis(triphenylphos-phine)copper(I) tctrahydroborate. C. atecholborune. 

When the product obtained from this oxidation of (41) is subsequently hydrolysed by snake venom phosphodiesterase in P OJHaO, a process in which the configuration at phosphorus is retained, and the chirality of the resulting 2 -deoxy-thymidine 5 -[ 0, 0, 0]phosphate analysed by cyclization to the 3, 5 -mono-phosphate, methylation and examination by P n.m.r., it is seen that the replacement of sulphur in (41) by proceeds with inversion at phosphorus, giving (43). Similarly, oxidation of (42) affords (44). Methylation of the potassium 18-crown-6 salt of (43) with methyl iodide gives the (i p)(45) and (5 p)(46) diastereoisomers of the methyl phosphotriester, and (45) gives a signal at higher field in the P n.m.r. spectrum than (46). The results show that little, if any,... 

Oj have been studied in toluene solution of the potassium 18-crown-6 salt. With spin traps adducts are observed mainly derived from 0 , derived from reaction (45). Reactions of superoxide, Oj, with ascorbic acid involve deprotonation... 

Dang and Kollman employed the thermodynamic perturbation theory with a modified version of the AMBER force field to determine the potential of mean force (PMF) to estimate the binding free energy of association of 18-crown-6 and The study represents one of the first FEP studies using a noncovalent association between a large neutral system and an ion. The initial coordinates of the complex were taken fi-om an X-ray structure of a potassium-18-crown-6 complex. The AAG ia for the association of the... 

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