Intermediate compounds preparation

The various intermediate compounds may be prepared in the laboratory, and convenient methods are described below. 

Almost as soon as Pedersen announced his discovery of the crown ethers (see Chaps. 2 and 3) it was recognized by many that these species were similar to those prepared by Busch and coworkers for binding coinage and transition metals (see Sect. 2.1). The latter compounds contained all or a predominance of nitrogen and sulfur (see also Chap. 6) in accordance with their intended use. The crown ethers and the polyazamacrocycles represented two extremes in cation binding ability and preparation of the intermediate compounds quickly ensued. In the conceptual sense, monoazacrowns are the simplest variants of the macrocyclic polyethers and these will be discussed first. 

Ethyl Acetoacetate. -The e. planation of the manner in which this substance is produced has been given in the account of the preparation. The result was anived at, not by the iscila-tion of the intermediate compound formed by the union of ethyl acetate with sodium ethylate, but by analogy with the behaviour of benzoic methyl ester with sodium benzylate, which gave the same additive product as that obtained by combining benzoic benzyl ester with sodium methylate, showing that such combinations could occur,... 

Another route presented in the work cited above also finally furnished 16 and 17, although in this case, the intermediate 62, prepared in three steps from indigo (63) via the 0-acetates 64 and 65, served as the precursor leading to the key compound 61 (Scheme 10) [97H(45)1647]. Details of the synthesis of 64 had been given previously by Bergman (82CS193). 

Synthetically, vicinal functionally substituted aryl- and hetarylacetylenes are promising intermediates for preparing different condensed heterocyclic compounds, taking into account the fact that these polyfunctional groups can be selectively involved in cyclization processes. 

To a mixture of 3.0 grams of N,N -diacetyl-o-anilamide and 20 ml of acetic acid Is added a previously prepared solution of 1.5 grams of chlorine in 31 cc of acetic acid. The reaction mixture is allowed to stand at room temperature for 3 hours and is then evaporated to dryness on a steam bath under reduced pressure. The resulting solid residue is recrystallized from ethanol, yielding the intermediate N,N -diacetyl-2-sulfamyl-4-chloroaniline. The intermediate compound is fused in an oil bath at 250-260°C for 15 minutes, cooled and the product so obtained is crystallized from 80% ethanol yielding 3-methyl-7-chloro-1,2,4-benzo-thiadiazine-1,1-dioxide, MP 330°C. 

Preparation of Intermediate Compound N-Acetyl-5-Chloro-2-Methylaniline To a well-stirred mixture of 1,270 g (9 mols) of 5-chloro-2-methylaniline in 7.5 liters of water at 34°C was added all at once 1,710 ml (18 mols) of acetic anhydride. A solution was obtained and then almost immediately the product started to crystallize. The temperature rose to 60°C. The mixture was stirred until the temperature dropped to 30°C. The product was filtered and washed well with water. Yield 97% (1,640 g), MP 134° to 138°C. Product was air dried and then in vacuum over PjOs. 

Preparation of Intermediate Compound 4-Chloro-5-Sulfamyl-N-Acetylanthranilic Acid To a hot solution (80°C) of 366 g (1.482 mols) of magnesium sulfate (Epsom salts) in 2.8 liters of water was added 130 g (0.495 mol) of powdered 5-chloro-2-methyl-4-sulfamyl-acetanilide. With stirring and maintaining the temperature at 83°C, 234 g (1.482 mols) of potassium permanganate was added portionwise over a period of 2 hours. The mixture was then kept at 85°C with stirring for an additional 3 hours. By this time the pink color of the permanganate had been discharged. 

Preparation of Intermediate Compound 2-Methyl-3-o-Tolyl-6-Sulfamyl-7-Chloro-4(3H)-Quinazoiinone Set up a 5-liter 3-necked flask fitted with a stirrer, condenser and a drying tube. To a stirred mixture of 100 g (0.342 mol) of powdered 4-chloro-5-sulfamyl-N-acetylanthranilic acid, 40.2 g (0.376 mol) of o-toluidine and 2.0 liters of dry toluene was added dropwise, over a period of 15 minutes, 21.7 ml (34.1 g) (0.248 mol) of phosphorus trichloride. The mixture was then refluxed for 10 hours. The solid turned somewhat gummy towards the latter part of the first hour. The mixture then became more free flowing as heating was continued. Let stand overnight. The yellow solid was filtered, washed with toluene and dried. The toluene filtrate was discarded. The dried solid was triturated with 1.5 liters of 10% sodium bicarbonate, filtered and the cake washed with water. The filtrate on acidification yielded 11.5 g of the starting acid. The damp product was dissolved in 4,5 liters of 95% ethanol and the solution treated with charcoal and filtered. On cooling filtrate yielded 69.5 g (55.5%) of the title compound, MP 271.5° to 274°C. 

The Sr-Cu system has been critically assessed. The most recent phase diagram, determined by combining differential thermal analysis and x-ray diffraction techniques, contains two intermediate compounds, both of which form in peritectic reactions, SrCu (588°C) and SrCu, (845°C) SrCu has also been prepared for independent structural analysis-. ... 

When solids react, we would like to know at what temperature the solid state reaction takes place. If the solid decomposes to a different composition, or phase, we would like to have this knowledge so that we can predict and use that knowledge In preparation of desired materials. Sometimes, intermediate compounds form before the final phase. In this chapter, we will detail some of the measurements used to characterize the solid state and methods used to foUow solid state reactions. This will consist of various types of thermal analysis (TA), including differentlEd thermal analysis (DTA), thermogravimetric analysis (TGA) and measurements of optical properties. 

The above compound, prepared as an intermediate to 1,3,3-trinitroazetidine for study as an explosive, decomposed explosively when heated above 120°C for distillation. Precautions when handling nitroazetidines are counselled. 

Clive and coworkers have developed a new domino radical cyclization, by making use of a silicon radical as an intermediate to prepare silicon-containing bicyclic or polycyclic compounds such as 3-271 and 3-272 (Scheme 3.69) [109], After formation of the first radical 3-267 from 3-266, a 5-exo-dig cyclization takes place followed by an intramolecular 1,5-transfer of hydrogen from silicon to carbon, providing a silicon-centered radical 3-269 via 3-268. Once formed, this has the option to undergo another cyclization to afford the radical 3-270, which can yield a stable product either by a reductive interception with the present organotin hydride species to obtain compounds of type 3-271. On the other hand, when the terminal alkyne carries a trimethylstannyl group, expulsion of a trimethylstannyl radical takes place to afford vinyl silanes such as 3-272. 

A complete run should if possible be made without stopping. However, if the preparation must be stopped before completion, the absorption vessels should be disconnected, weighed, and protected against moisture by calcium chloride tubes. They lose weight on standing owing to decomposition of the intermediate compound. 

US patent 6,753,426, Polymorph and process for preparing same [111], In this patent are disclosed are processes, a new polymorph, and intermediate compounds for preparing various aryl- and heteroaryl-substituted urea compounds. The product compounds are useful in pharmaceutical compositions for treating diseases... 

The [3.3.3]propellane skeleton could also be prepared from the cyclobutene (282), which provided the product (283). The propellane (283) was an intermediate compound in the synthesis of modhephene (284) 96K... 

Some synthetically important allenylmetallics, such as allenylzinc and allenylin-dium reagents, are prepared from allenylpalladium intermediates. These reactions are discussed in appropriate sections of this chapter. This section covers the reactions of allenylpalladium compounds without further transmetallation. Allenylpalladium complexes can be prepared from propargylic halides, acetates, carbonates, mesylates, alcohols and certain alkynes [83-87], The allenylpalladium compound prepared from 3-chloro-3-methyl-l-butyne has been isolated and characterized spectroscopically (Eq. 9.106) [83], It was found to couple with organozinc chlorides to produce homologated allenes quantitatively (Eq. 9.107). 

Hegedus and co-workers8 reported the synthesis of (4S,5R)-4,5-diphenyl-3-vinyl-2-oxazolidinone (the enantiomer of the compound prepared here) via the chromium carbene complex in a fair yield. This is an interesting method, but the procedure is complicated (e.g., low temperature, argon atomsphere) and the chromium waste must be disposed of in an appropriate way. On the other hand, this procedure, consisting of transacetalization9 and pyrolysis,10 is simple and safe. Optically active 3-vinyl-2-oxazolidinone is also used for the synthesis of (1 R,2S)-2-fluorocyclopropylamine11a b that is the key intermediate for novel antibacterial quinolonecarboxylic acids. 

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