Synthesis nucleophilic displacement

Polyetherimide synthesis has been achieved by reaction of a dianhydride containing an ether linkage with a diamine, reaction of a diamine containing an ether linkage with a dianhydride, or nucleophilic displacement of halo or nitro groups of a bisimide by bisphenol dianion (19,20). Such Pis exhibit good thermal stabiUty and melt processibiUty. 

Syntheses. The presence of the ether and imide functionahties provides two general approaches for synthesis. Polyetherimides can be prepared by a nucleophilic displacement polymerkation similar to the haUde displacement inpolysulfone synthesis or by a condensation of dianhydrides and diamines that is similar to normal polyimide synthesis (see POLYIMIDES). 

Solvent for Displacement Reactions. As the most polar of the common aprotic solvents, DMSO is a favored solvent for displacement reactions because of its high dielectric constant and because anions are less solvated in it (87). Rates for these reactions are sometimes a thousand times faster in DMSO than in alcohols. Suitable nucleophiles include acetyUde ion, alkoxide ion, hydroxide ion, azide ion, carbanions, carboxylate ions, cyanide ion, hahde ions, mercaptide ions, phenoxide ions, nitrite ions, and thiocyanate ions (31). Rates of displacement by amides or amines are also greater in DMSO than in alcohol or aqueous solutions. Dimethyl sulfoxide is used as the reaction solvent in the manufacture of high performance, polyaryl ether polymers by reaction of bis(4,4 -chlorophenyl) sulfone with the disodium salts of dihydroxyphenols, eg, bisphenol A or 4,4 -sulfonylbisphenol (88). These and related reactions are made more economical by efficient recycling of DMSO (89). Nucleophilic displacement of activated aromatic nitro groups with aryloxy anion in DMSO is a versatile and useful reaction for the synthesis of aromatic ethers and polyethers (90). 

Extension of the Phosphorane Route. Ample evidence of the versatihty of the phosphorane synthesis strategy is provided by the proliferation of penems that followed. Nucleophilic displacement of the acetate function of the acetoxy-azetidinone (51, R = OCOCH ) [28562-53-0] (86) provided azetidinones where R = SCOCH, SCSSC2H, and SCSOC2H, which on elaboration gave the penems (52, R = CH ) (87), (52, R = SC2H ) (88), (52, R = 0C2H ) (89). Similar treatment of 3-substituted (or disubstituted) acetoxyazetidinones allowed the synthesis of a number of 2-substituted- 6-alkyl-and 6,6-dialkylpenems (90). 

H-Azepine, 2-allyloxytetrahydro-Claisen rearrangement, 7, 508 3H-Azepine, 2-amino-acylation, 7, 511 effect of acidification, 7, 510 nucleophilic displacement reactions, 7, 514 synthesis, 7, 533, 535 3H-Azepine, 2-amino-7-bromo-synthesis, 7, 529 3H-Azepine, 2-anilino-ring inversion, 7, 495-499 structure, 7, 533... 

Imidazolidin-2-one, l-(5-nitro-2-thiazolyl)-pharmacological activity, 6, 328 Imidazolidin-4-one, l-aryl-3-phenyl-2-thioxo- C NM S, 355 Imidazolidinones C NMR, 5, 355 Imidazolidin-2-ones nucleophilic displacement, 5, 428 polymers, 1, 279-280 reactivity, 5, 376 synthesis, 5, 466, 471 Imidazolidin-4-ones synthesis, 5, 468 Imidazoline, 2-alkyl-synthesis, 5, 463 Imidazoline, 2-amino-applications, 5, 498 Imidazoline, 2-aryl-synthesis, 5, 463 Imidazoline, 2-methyl-synthesis, 5, 487 Imidazoline, 2-nitroamino-synthesis, 5, 471 2-Imidazoline, 2-arylamino-tautomerism, 5, 368 2-Imidazoline, 1-benzyl-methylation, 5, 425 2-Imidazoline, 1,2-diaryl-synthesis, 5, 463... 

Imidazo[l,2-c]pyrimidine, 2,5,7-trichloro-nucleophilic displacement reactions, 5, 627 Imi dazo[ 1,2-a]pyrimidines pK, 3, 338 reactivity, 5, 627 synthesis, 5, 647 Imidazo[ 1,2-c]pyrimidines reactions, 5, 627 structure, 5, 610 synthesis, 5, 648-649 lmidazo[ 1,5-a]pyrimidines reactions, 5, 628 synthesis, 5, 649 lmidazo[l,5-6]pyrimidines synthesis, 5, 649-650 Imidazopyrrolopyridines bromination, 4, 506 lmidazo[4,5-6]quinoxaline nomenclature, 1, 22... 

Pyrazolino[2,3-c][l,2,3]triazoles, 5, 702 Pyrazolium hydroxide, l,2-dimethyl-3,5-diphenylanhydro-4-hydroxy-IR spectra, 5, 201 Pyrazolium salts dequatemization, 5, 269 H NMR, 5, 185 hydrogen exchange at ring carbon, 5, 245 mesoionic compounds, 5, 171 nitrodebromination, 5, 237 reactivity, 5, 217 reduction, 5, 68, 243 synthesis, 5, 156 UV spectra, 5, 199 Pyrazolium salts, amino-reactions, 5, 262 Pyrazolium salts, bromo-nucleophilic displacements, 5, 266 Pyrazolium salts, 1,2-dimethyl-deuteration, 5, 175, 245 hydrogen exchange, 5, 71 acid-catalyzed, 5, 239 reactions... 

H-Pyrido[3,2-c]azepine, 7-methoxy-nucleophilic displacement reactions, 7, 514 Pyridoazepines synthesis, 7, 535, 540 Pyridoazepinones synthesis, 7, 531 Py rido[2,1-a]benzazepin-6-one physiological properties, 7, 546 Py rido[ 1,2-a]benzimidazoles reactions, 6, 1041... 

Pyrimidine, I-alkyl-2-methyltetrahydro-C-thioacylation, 4, 807 Pyrimidine, 4-alkylsulfinyl-nucleophilie displaeement reaetions, 3, 97 Pyrimidine, 6-alkylsulfinyl-nucleophilic displacement reactions, 3, 97 Pyrimidine, 2-alkylsulfonyl-nueleophilie displaeement reactions, 3, 97 Pyrimidine, 4-alkylsulfonyl-nucleophilic displacement reactions, 3, 97 Pyrimidine, 6-alkylsulfonyl-nucleophilie displaeement reactions, 3, 97 Pyrimidine, alkylthio-dealkylation, 3, 95 desulfurization, 3, 95 oxidation, 3, 96 synthesis, 3, 135, 136 Pyrimidine, 2-alkylthio-aminolysis, 3, 96 hydrolysis, 3, 95 Prineipal Synthesis, 3, 136 Pyrimidine, 4-alkylthio-aminolysis, 3, 96 hydrolysis, 3, 95 Pyrimidine, 6-alkylthio-aminolysis, 3, 96 hydrolysis, 3, 95 Pyrimidine, 4-allenyloxy-rearrangement, 3, 93 Pyrimidine, 4-allyloxy-2-phenyl-rearrangement, 3, 93 Pyrimidine, 4-allynyloxy-rearrangement, 3, 93 Pyrimidine, 4-anilino-2,5,6-trifluoro-NMR, 3, 63 Pyrimidine, 2-aryl-pyrroleaeetic aeid from, 4, 152 Pyrimidine, arylazo-synthesis, 3, 131 Pyrimidine, 4-arylazo-reduetion, 3, 88... 

H-Pyrimido[l, 2-6]pyridazin-2-one, chloro-nucleophilic displacement reactions, 3, 343 2H-Pyrimido[l,2-6]pyridazin-2-one, 7-chloro-synthesis, 3, 354... 

Thiazolin-5-one, 2-alkoxy-4-arylazo-rearrangements, 5, 777 2-Thiazolin-5-one, 4-methyl-2-phenyl-protomeric equilibrium, 6, 249 4-Thiazolin-2-one, 4-aryl-reactions, 6, 286 4-Thiazolin-2-one, 3,4-dimethyl-protonation, 6, 286 4-Thiazolin-2-one, 4-methyl-reactions, 6, 286 Thiazolinones electrophilic attack, 5, 99 Thiazolin-2-ones IR spectroscopy, 6, 241 nucleophilic displacement, 5, 100 2-Thiazolin-4-ones reactions, 6, 287 2-substituted synthesis, 6, 306 synthesis, 5, 129 6, 309, 310 tautomerism, 6, 248 2-Thiazolin-5-ones IR spectroscopy, 6, 242 reactions, 6, 288 synthesis, 5, 138 tautomerism, 6, 249 4-Thiazolin-2-ones synthesis, 6, 314 4-Thiazolin-3-ylacetic acid esters... 

In a penicillin synthesis the carboxyl group was protected as a p-bromophenac ester that was cleaved by nucleophilic displacement (PhSK, DMF, 20°, 30 mil... 

In a penicillin synthesis, the carboxyl group was protected as a / -bromophenacyl ester that was cleaved by nucleophilic displacement (PhSK, DMF, 20°, 30 min, 64% yield). Hydrogenolysis of a benzyl ester was difficult (perhaps because of catalyst poisoning by sulfur) basic hydrolysis of methyl or ethyl esters led to attack at the /3-lactam ring. ... 

A new synthesis of unsaturated azlactones, which is especially useful in cases where the aldehyde is not readily available, has been developed. The reaction involves the nucleophilic displacement of chlorine in 4-chloromethylene-2-phenyl-5(4Z )-oxazolone (6) by a... 

Because of the ease of ring synthesis, symmetrically trisubstituted s-triazines have been more thoroughly studied, but a few nucleophilic substitutions of derivatives bearing a single leaving group are known. 2-Chloro-4,6-diphenyl- and 2-chloro-4,6-dimethyl-s-triazines (318) undergo facile nucleophilic displacements with ammonia, amines, and hydrazine, with alkoxide, or with hydrosulfide... 

Intramolecular nucleophilic displacement reactions of aromatic nitro group by various nucleophiles include cydization reactions, which provide practical methods for the synthesis of a variety of heterocycles. 1 hope that the text of this review suggests a wide range of potential of this reaction in organic synthesis of various heterocycles. However, it is necessary to stress that some structural types described in this review could be prepared with similar, or even better yields by other methods. In spite of this, there are many heterocyclic systems for the synthesis of which the denitrocyclization strategy is a method of choice. 

Nucleophilic displacement reactions One of the most common reactions in organic synthesis is the nucleophilic displacement reaction. The first attempt at a nucleophilic substitution reaction in a molten salt was carried out by Ford and co-workers [47, 48, 49]. FFere, the rates of reaction between halide ion (in the form of its tri-ethylammonium salt) and methyl tosylate in the molten salt triethylhexylammoni-um triethylhexylborate were studied (Scheme 5.1-20) and compared with similar reactions in dimethylformamide (DMF) and methanol. The reaction rates in the molten salt appeared to be intermediate in rate between methanol and DMF (a dipolar aprotic solvent loiown to accelerate Sn2 substitution reactions). 

As a demonstration of the complete synthesis of a pharmaceutical in an ionic liquid, Pravadoline was selected, as the synthesis combines a Friedel-Crafts reaction and a nucleophilic displacement reaction (Scheme 5.1-24) [53]. The allcylation of 2-methylindole with l-(N-morpholino)-2-chloroethane occurs readily in [BMIM][PF6] and [BMMIM][PF6] (BMMIM = l-butyl-2,3-dimethylimida2olium), in 95-99 % yields, with potassium hydroxide as the base. The Friedel-Crafts acylation step in [BMIM][PF6] at 150 °C occurs in 95 % yield and requires no catalyst. 

Recently, the above mentioned model reaction has been extended to polycondensation reactions for synthesis of polyethers and polysulfides [7,81]. In recent reports crown ether catalysts have mostly been used in the reaction of a bifunctional nucleophile with a bifunctional electrophile, as well as in the monomer species carrying both types of functional groups [7]. Table 5 describes the syntheses of aromatic polyethers by the nucleophilic displacement polymerization using PTC. 

TNT-based condensation monomers. The synthesis of these materials is presented humorously by Russian authors a as consequence of the end of the Cold War. The synthesis, based on a very easy nucleophilic displacement of an activated nitro group, offers many possibilities for the synthesis of diamines bearing a functional group.117... 

The synthesis of polyether quinoxaline by nucleophilic displacement discussed in Section 5.4.2.2 has also been used for the preparation of hyperbranched polyquinoxaline based on AB2 or A2B monomers. In the AB2 monomer the focal point is a single fluoro group (Fig. 5.42)172 in the A2B the focal point is a single... 

Nucleophilic displacement, PQ and PPQ synthesis by, 310-311 Nucleophilic substitution, 10, 282, 283 hyperbranched polyimides via, 308 Nucleophilic synthesis, of bisphenol-A polysulfone, 337... 

Nucleophilic Displacement Reactions in Carbohydrates. Part XI. Reaction of Methyl 6-Deoxy-2,3-O-isopropylidene-4-O-methyl-sulphonyl-a-L-talopyranoside with Sodium Azide A Synthesis of L-Perosamine (4-Amino-4,6-dideoxy-L-mannose) Derivatives, J. S. Brimacombe, O. A. Ching, and M. Stacey, J. Chem. Soc. C, (1969) 1270-1274. 

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