Lithium chloride-Dimethylformamide

In addition, 85-90% yields of neryl chloride could be obtained from nerol, the geometrical isomer of geraniol. A modification4 of the above method has appeared which employs methanesulfonyl chloride and a mixture of lithium chloride, dimethylformamide, and collidine at 0° however, its applicability to compounds possessing sensitive groups was not demonstrated. 

Lithium chloride dimethylformamide ammonia Ethylene- from chloro-lactams... 

The bromination of 4,5-j -dihydrocortisone acetate in buffered acetic acid does not proceed very cleanly (<70%) and, in an attempt to improve this step in the cortisone synthesis, Holysz ° investigated the use of dimethylformamide (DMF) as a solvent for bromination. Improved yields were obtained (although in retrospect the homogeneity and structural assignments of some products seem questionable.) It was also observed that the combination of certain metal halides, particularly lithium chloride and bromide in hot DMF was specially effective in dehydrobromination of 4-bromodihydrocortisone acetate. Other amide solvents such as dimethylacetamide (DMA) and A-formylpiperidine can be used in place of DMF. It became apparent later that this method of dehydrobromination is also prone to produce isomeric unsaturated ketones. When applied to 2,4-dibromo-3-ketones, a substantial amount of the A -isomer is formed. 

A solution of betamethasone 21-methanesulfonate (4 g) in dimethylformamide (25 ml) was treated with lithium chloride (4 g) and the mixture heated on the steam bath for 30 minutes. Dilution with water gave the crude product which was recrystallized to afford the title compound, MP 226°C. 

IB) 21-Chloro-90i-fluoro- -pregnene-11 160l,170i-triol-3,2Q-d ane 16,17-acetonlde A solution of 200 mg of the acetonide 21-mesylate from part (A) and 900 mg of lithium chloride in 25 ml of dimethylformamide is kept at 100°C for 24 hours. The mixture is poured on ice, extracted with chloroform and the chloroform extract washed with water and dried over sodium sulfate. Evaporation of the solvent in vacuo furnishes the crystalline chloride, which after recrystallization from acetone-ethanol has a melting point about 276°C to 277°C. 

The oxidation of n-butanal by CUCI2 in dimethylformamide showed simple second-order kinetics in the presence of lithium chloride . At 83 °C, 2 s 2x10 1.mole". sec". a-Monohalogenation occurs in 97% yield. Cu(Il)-catalysed enolisation followed by ligand-transfer is proposed. a-Halogenation of acetone is accomplished by CUCI2, viz. 

The palladium-catalyzed cross-coupling reaction featured in this procedure occurs under neutral conditions in the presence of many synthetically useful functional groups (e.g. alcohol, ester, nitro, acetal, ketone, and aldehyde). The reaction works best in N,N-dimethylformamide with bis(triphenylphosphine)palladium(ll) chloride, PdCI2(PPh3)2, as the catalyst. Lithium chloride is added to prevent decomposition of the catalyst.143 13 It is presumed that conversion of the intermediate aryl palladium triflate to an aryl palladium chloride is required for the transmetallation step to proceed.9... 

C. 4-Methoxy-4 -nitrobiphonyl (3). A dry, 500-mL, three-necked, round-bottomed flask equipped with a reflux condenser, magnetic stirring bar, nitrogen gas inlet, and rubber septum (Note 1) is charged sequentially with 300 mL of anhydrous N,N-dimethylformamide (Note 13), 15.0 g (55.4 mmol) of 4-nitrophenyl trifluoromethanesulfonate (1), 27.8 g (70.0 mmol) of tributyl(4-methoxyphenyl)stannane (2) (Note 14), 7.5 g of dry lithium chloride (Note 15), and 1.6 g (4 mol percent) of bis(triphenylphosphine)palladium(ll) chloride (Note 16). The rubber septum is replaced with a Teflon stopper and the yellow mixture is heated at 100-105°C for 2.5 hr. After approximately 20 min, the reaction turns dark brown. 

The synthesis of halcinonide is summarized in Figure 1, starting with 16a-hydroxy-9a-fluorohydrocortisone (A1 -pregnene-9a-fluoro-llg,16a,17a,21-tetrol-3,20-dione dihydrotriamcinolone, I), which is available commercially.10-13 This tetrahydroxy steroid is slurried in acetone, and then 70% perchloric acid is added slowly. The acetonide, II (9a-fluoro-llg, 16a, 17, 21-tetrahydroxypregn-4-ene-3, 20-dione, cyclic 16,17-acetal with acetone dihydrotriamcinolone-acetonide) precipitates spontaneously from solution. Mesyl chloride is added to the acetonide in pyridine to give the 21-mesylate derivative (dihydrotriamcinolone acetonide-21-mesylate, III). Compound III is dissolved in dimethylformamide, lithium chloride is added and the mixture is refluxed to produce halcinonide (IV), which is recrystallized from a solution of ft-propanol in water. 

Chloro-6-deoxy-l,2 3,4-di-0-isopropylidene-a-D-galactopyranose has been obtained in 96% yield by treatment of l,2 3,4-di-0-isopropylidene-6-0-p-tolylsul-fonyl-a-D-galactopyranose with lithium chloride inN,N-dimethylformamide [see K. W. Buck and A. B. Foster,/. Chem. Soc., 2217 (1963)]. 

Most linear ceilulosics may be dissolved in solvents capable of breaking the strong hydrogen bonds. These solvents include aqueous solutions of inorganic acids, zinc chloride, lithium chloride, dimethyl dibenzyl ammonium hydroxide, and cadmium or copper ammonia hydroxide (Schweizer s reagent). Cellulose is also soluble in hydrazine, dimethyl sulfoxide in the presence of formaldehyde, and dimethylformamide in the presence of lithium chloride. The product precipitated by the addition of nonsolvents to these solutions is highly amorphous and is called regenerated cellulose. 

Nonafluoro-l-iodopentane (6) on heating with lithium chloride in dimethylformamide gives 2//-nonafluoropent-l-enc (7).11... 

The 3-keto-84 system is introduced by conventional methods, that is, by oxidation of the 3-hydroxy group to a 3-keto group with chromic oxide. Bromination at the 4-position, and finally dehydrobromination with dinitrophenylhydrazine or with lithium chloride in dimethylformamide were carried out to give acetic acid lip-hydroxy-3,18,20-trione-pregn-4-ene lip,18-lactone 17-oxoethyl ether. 

Electrochemical generation of strong base has been applied in an interesting modification of the Wittig reaction 161 A solution of azobenzene, benzaldehyde, benzyltriphenylphosphonium bromide, and lithium chloride in dimethylformamide was electrolyzed at a potential where only the easily reducible azobenzene was electroactive. The phosphonium ion then acts as a proton source, giving the ylide as an intermediate. Under these conditions a 98 % yield of a mixture of cis- and trans-stilbene was obtained, presumably via the following reactions ... 

Reaction of the diol with p-toluenesulfonyl chloride in pyridine, however, produced the ditosylate in nearly quantitative yield. SN2 displacements by chloride on neopentyl tosylate, which bears certain structural similarities to the ditosylate precursor of CAMPHOS, have been shown to give good yields of neopentyl chloride. However, when l,2,2-trimethyl-l,3-bis(hydroxymethyl)-cyclopentane ditosylate was allowed to react with sodium chloride in hexa-methylphosphoramide, in an attempt to form the dichloride, only N, A -dimethyl-p-toluenesulfonamide was isolated. Reaction of the ditosylate with lithium chloride in ethoxyethanol was exothermic and HC1 was evolved but the dichloride was not isolated. The isolated product contained at least one oleflnic bond. Similarly, in N, TV-dimethylformamide, lithium chloride and the ditosylate gave a product that decomposed on distillation. Faced with such repeated failures, a dihalide route to CAMPHOS was abandoned in favor of a more direct approach reaction of the ditosylate with diphenylphosphide anion. 

Cellulose can also blend with natural or synthetic polymers to produce adhesives. The recent development of new cellulose solvents(iO), such as lithium chloride/dimethyacetamide solvent, dinitrogen tetroxide/dimethylformamide solvent, dimethyl sulfoxide/paraformaldehyde solvent, have provided the potential to produce uniform cellulose polyblends. 

Dehydrohalogenation. With use of this reagent in refluxing dimethylformamide. House and Bashe were able to effect dehydrobromination of the bromoketone (1) to the unrearranged product (2). Use of the less basic lithium chloride led to... 

Use of this combination in dimethylformamide for effecting dehydrohalogenation was introduced by Joly as an improvement of the method of Holysz using lithium chloride in DMF. As applied to 2j3,4j8-dibromo-l 7j8-acetoxyetiocholane (I), the... 

Disconnection between C=0 and C=C with the aliphatic Friedel-Crafts reaction in mind would require acylation of the unsymmetrical alkene 76 with the acid chloride 77. The alkene 76 is ideal for acylation as it is tri-substituted and therefore relatively electron-rich and will react at the required (less substituted) end. The P-chloroketone 78, formed when SnCl4 was used as the Lewis acid, was treated with base without isolation to give the enone 74 in 60% overall yield. Lithium chloride may not look very basic, but in dipolar aprotic solvents like DMF (DiMethylFormamide, Me2NCHO), that do not solvate anions, chloride is a good base. 

Dimethylformamide-Lithium chloride, 274 Dimethylformamide-Thionyl chloride, 116,... 

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