Piperazino piperazines

Under microwave heating conditions compound 46 is obtained with reduced reaction time (1.5 h) and better purity. A dramatic improvement was achieved when 46 was treated with N-methyl piperazine in DMF in a sealed glass vessel. After 1 h under microwave irradiation, the N-methyl piperazino derivative 47 was obtained in 68 % yield. 

Macrocycle 177 in which the 2,6-pyridino and the 1,4-piperazino moieties were incorporated into the macrocyclic framework has been reported. The synthesis of 177 (10%) was accomplished by treatment of 2,6-dichloropyridine with the dianion of Ar,Ar -W. (2-hydroxyethyl)piperazine in refluxing xylene. Attempts to prepare the cobalt(II) complex of 177 resulted in diprotonation of the macrocycle. The X-ray crystal structure determination analysis has been performed for both 177 and 178. According to the crystal structure analysis of 178, the piperazine rings are in the chair conformation in the solid state and the molecule is fairly rigid due to the imposed steric constraints of the imidate moieties l39). 

The N-alkylation, N-arylation, and in particular N-heteroarylation of piperazines is an important process because of the common propensity (justified or not) for introducing a piperazino grouping into structures perceived as potentially bioactive in a variety of drug-related areas. The various routes to such N-alkylated piperazines are outlined in this section, which also includes examples of the N-alkylation of di- or tetrahydropyrazines the N-alkylation of (tautomeric) pyrazinones and the like is covered in Section 5.1.2.2. 

The most practical route used in the synthesis of numerous 6,7-dimethoxy-2-(l-piperidyl)- or 6.7-diniethoxy-2- piperazin-l-yl)quinazolin-4-amines substituted with various chemical groups in the piperidino or piperazino moiety, which are analogs of the hypotensive agent prazosin, is the cyclization of 5-methylisothioureas 1 with an excess of ammonium chloride. The highly pure hydrochlorides 2 are obtained in yields of more than... 

Von den eingesetzten sek. Aminen gibt das mit 4-Methyl-piperazin erhaltene Bis-[4-me-thyl-piperazino]-aluminiumhydrid die besten Aldehyd-Ausbeuten ... 

In Figure 2, A, the piperazino group usually leads to more active compounds than the dimethylamino group. On the terminal nitrogen of the piperazine the N-/3-hydroxy ethyl group leads to higher activity than the N-methyl. 

The only reference to this ring system names the perhydro heterocycle as piperazino[l,2-a]piperazine. Reduction of the 2,4-dinitrophenyl-hydrazone 1 with Raney nickel gave the dioxo derivative 2 in 26% yield. This compound was reduced with lithium aluminum hydride to give the product 3. 

Chloro-47/-pyrido[l,2-a]pyrimidine-4-thione was obtained by the treatment of the 4-oxo derivative with Lawesson s reagent in boiling anhydrous toluene, and then the 2-chloro atom was changed for a piperazino group with piperazine in boiling EtOH (00BMC751). Treatment of 7-chloro-3-propyl-2-propoxy-4/f-pyrido[ 1,2-a]pyrimidin-4-one with... 

The rates increase with increasing dielectric constant, and H20+Br is the reactive oxidant species. The oxidation of [2-(2- 4-[(4-chlorophenyl)(phenyl)methyl]-l-piperazino ethoxy) acetic acid dihydrochloride (CTZ) by BAT in HCl has a negative fractional dependence in H+ ion, and the rates decrease with increasing dielectric constant of the solvent. CH3C6H5S02NHBr is the reactive BAT species. " The oxidation of cetrizine dihydrochloride (CTZH) with BAT has been investigated both in acid and alkaline medium. A negative fractional order in H+ ion and positive fractional order in HO ion are reported, accompanied by a fractional order in CTZH in both acidic and alkaline media. The rate increases with increasing dielectric constant of the solvent. The reaction in alkaline medium has fractional order in p-toluenesulfonamide (PTS). The oxidation rate of CTZH is faster in acid medium and 4-chlorobenzophenone and (2-piperazine-l-yl-ethoxy)-acetic acid are the oxidation products. ... 

The S-atom uronamide replacement 175 has been described, the presence of 5-bromouracil giving increased stability to duplexes compared with the thymidine case, and similar dimers involving a-thymidine have also been reported. The piperazino-linked dimers 176 and 177 have been prepared and incorporated into oligonucleotides. The piperazine unit was attached to the... 

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