Piperazines preparations

A solution of 54.1 grams of 1-formyl-4-(3 -chloropropyl)-piperazine, [prepared by formylat-ing 1-(3 -hydroxypropyl)-piperazine by refluxing in an excess of methyl formate, purifying the 1-formyl-4-(3 -hydroxypropyl)-piperazine by vacuum distillation, reacting this compound with an excess of thionyl chloride at reflux and isolating the desired 1-formyl-4-(3 -chloropropyl)-piperazine by neutralization with sodium carbonate solution followed by distillation] in 200 ml of toluene is added. The reflux period Is continued for 4 hours. 

Piperazine is a diethylenediamine used extensively in swine and chickens, but seldom in cattle and sheep. Piperazine preparations can be administered via either the feed or drinking water at a dosage of 275-440 mg/kg bw to pigs and 250 mg/kg bw to chickens. 

Table 1 Selected 4-(2-pyridyl)-piperazine prepared according to the aforementioned method. Entry 1 is especially preferred. Very limited physical data supplied by author...

Polymers have also been prepared from cyclic amines such as piperazine and bis-(p-aminocyclohexyl)methane. An early copolymer, Igamid 1C, was based on the latter amine. This amine is also condensed with decanedioic acid, HOOC (CH2)iqCOOH, to produce to silk-like fibre Quiana (Du Pont). 

Preparation of the substituted piperazine required for sul-falene (114) starts with bromination of 2-aminopiperazine to give the dihalide (150). Displacement of halogen by sodium methoxide proceeds regioselectively at the more reactive 3 position to give 151. Hydrogenolysis over palladium on charcoal gives the desired intermediate (152). 

The most complex side chain of the piperazine phenothiazines is to be found on chlorimpiphenine (86). The side chain is prepared by first alkylating monocarbethoxypiperazine with the chlorobenzimidazole 83 [itself attainable by alkylation of methylbenzimidazole with a dihalide). Removal of the carbethoxy group affords the substituted piperazine, 85. Alkylation of this base with the chloropropyl phenothiazine, 58, affords finally the desired compound (86). ... 

Replacement of the terminal nitrogen of the piperazine by carbon is said to enhance the antiemetic activity of the phenothiazines at the expense of the other pharmacologic effects. The simplest compound in this series, pipamazine (88), is prepared by alkylation of nipecotamide (87) with the chloropropyl phenothiazine (58). Preparation of the analogous sulfoxide begins with acetylation of the thiomethyl compound, 89 [prepared by a route... 

This compound can be prepared by the reaction of cinnamoyl chloride with benzhydryl-piperazine. The reaction is carried out in dry benzene under reflux. The benzene is then evaporated, the residue taken up in chloroform, washed with dilute HCI and then made alkaline. 

Stage 2 Preparation of 1 -[2-Phenyi-2-Methoxy]-Ethyi-Piperazine — 210 grams of 2-phenyl-2-methoxy-ethyl bromide and 260 grams of anhydrous piperazine are heated for 5 to 6 hours to reflux in 600 ml of ethanol, 500 ml of ethanol is then distilled off and finally the solvent is removed in vacuo. The residue is taken up in 250 ml of benzene and the piperazine hydrobromide is filtered off. The benzene is removed in vacuo. The oily residue is taken up by 450 ml of water and acidification is effected up to pH = 1 by concentrated HCI. 

Stage 4 Preparation of 1-l2-Phenyi-2-Methoxyl -Ethyi-4-[3-Phenyl-3-Hydroxypropyl] -Piperazine Dihydrochioride - In a double-neck flask equipped with a thermometer and a mechanical stirrer, there is placed in suspension in 800 ml of methanol, 233 grams of 1-[2-phenyl-2-methoxy]-ethyl-4-[2-benzoyl-ethyl]-piperazine dihydrochioride (0.55 mol). It is cooled to approximately 5°C, and 46 grams of NaOH pellets dissolved in 80 ml of HjO are added. When the temperature is about 5°C, one addition of 29,2 grams of sodium borohydride in 40 ml HjO is made. The ice-bath is then removed and stirring continued at ambient temperature for 6 hours. 

A mixture of 50 grams of the above prepared piperazine, 30.1 grams of sodium carbonate and 200 ml of benzene is heated to reflux and treated with 39.5 grams of 3-bromopropanol over 1.5 hours. The resulting mixture is refluxed for 2 hours, then filtered, extracted with dilute hydrochloric acid, basified, extracted with benzene, and the extracts are concentrated and distilled to give 1-benzyloxyethyl-4-(3-hydroxypropyl)-piperazine, BP 1BB°to 190°C (0.15 mm). The free base is converted to the dihydrochloride salt by treatment of an alcoholic solution with ethereal hydrogen chloride to separate the salt. 

Thionyl chloride (67 grams) is added over 15 minutes to a mixture of 39.5 grams of the above prepared dihydrochloride salt and 400 ml of chloroform. Refluxing for 4 hours, cooling and filtering yields the dihydrochloride salt of 1-benzyloxyethyl-4-(3-chloropropyl)-piperazine, (VIP 201° to 202°C. The salt in aqueous solution is basified. Extraction with ether and evaporation of the solvent yields the free base. 

Preparation of N-(3-chlorQpropyl)-N -[2-(1,3-dioxanyl)-ethyl]-piperazine A solution of 30 g... 

The sodium derivative of the 2-trifluoromethylphenothiazine was prepared from 26.7 g (0.1 mol) of 2-trifluoromethylphenothiazine and 2.3 g (0.1 g atom) of sodium in 500 ml of liquid ammonia. After the reaction was completed, the ammonia was driven off and 500 ml of dry toluene were added. A solution of 25 g (0.09 mol) of N-(3-chloropropyl)-N -[2-(1,3-dioxanyl)-ethyl] -piperazine In 200 ml of toluene was added drop by drop to this solution which was then refluxed with stirring for 1B hours. After cooling, the precipitate which had formed was filtered and the filtrate was washed with water, dried and concentrated in vacuo. 33 g of brown oil, the N-3-(2-trifluoromethyl-10-phenothiazinyl)-propyl-N -2-[2-(1,3-dioxanyl)] -ethyl-piperazine, were obtained. 

Preparation of 2-f1-Piperazinyl)-4-Amino-6,7-Dimethoxyquinazoline To 5 g of 2-chloro-4-amino-6,7-dimethoxyquinazoline, is added 20 g of a 25% solution of piperazine in ethanol, The mixture is heated at 160°C for 16 hours in a pressure bottle. The solvent is then evaporated and the residue is recrystallized from methanol/water. 

Phosphorus containing poly(maleimide-amines) were synthesized from N,N -bisdichloromaleimido-3,3 -diphenyl alkylphosphine oxides and aromatic diamines or piperazine [144]. The polymers prepared from piperazine are soluble in DMF, DM AC, DMSO, etc., but have poor thermal stability and flame retardancy. 

Under carefully controlled conditions even complex molecules can be fluorinated. For example, the preparation of perfluoro-crown ethers (85CC1350) and perfluoro(2.2.2.)-cryptand (90JOC5933) has been described. Branched morpholines and piperazines have been directly fluorinated to their perfluoro analogues [90JFC(50)15],... 

Several cyclic glyphosate analogs related to this series were described previously as intermediates to prepare glyphosate. These include various N-phosphonomethylhydantoins and diketopiperazines. A more extended glyphosate piperazine analog 106 has also been prepared firom the Mannich reaction of ethylenediamine-lV,lV -diacetic acid (65). 

Quaternary ammonium salts of 1-acryloy 1-4-methyl piperazine can be prepared by methylation with methyl chloride and dimethyl sulfate. These monomers can be polymerized by means of radical polymerization, either alone or with a comonomer [617]. A useful comonomer with appropriate monomer reactivity ratios is acrylamide. 

Certain basic polyamides can be further prepared by reacting piperazine derivatives with amines [814]. 

A related and relatively simple quinoline derivative has been reported to exhibit antidepressant activity. Its preparation merely involves displacement of halogen in 12 with piperazine to afford quipazine (13).6... 

The presence of a rather more complex substituent on the remote piperazine nitrogen atom is consistent with tranquilizing activity. The preparation of one such agent, 16, begins with reaction of thioxanthone 11 (obtained by a sequence analogous to that used to... 

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