Aqueous piperidine

When allyladenine is incorporated into the strands of DNA, upon treatment of this with iodine and aqueous piperidine, an iodination-cyclization-depurination-hydrolysis sequence occurs to give a pyrazinopurine and cleave the DNA (Scheme 89) <1997CC1425>. 

Mc2S04 and aqueous formic acid, then aqueous piperidine cleavage at A and G ... 

Challis, B. C., and Kyrtopoulos, S. A. (1978). The chemistry of nitroso comptiunds. Part 12. The mechanism of nitrosation and nitration of aqueous piperidine hy gaseous dinitrogen tetraoxide and dinitrogen trioxide in aqueous alkaline solutions. Evidence for the existence of molecular isomers of dinitrogen tetraoxide and dinitrogen trioxide. J. Chem. Soc. Perkin Trans. 2, 1296-1302. 

The initial acylation is followed by selective demethylation at the most electron-rich ortho ether function of the benzophenone (73JCS(P1)1329). Cyclization to the xanthone is achieved in almost quantitative yield on boiling the benzophenone with aqueous alkali or with aqueous piperidine. Coupled with the selective demethylation of polymethoxybenzo-phenones or xanthones which is possible under acidic or basic conditions, this method provides an attractive and efficient synthesis of naturally occurring xanthones. 

Cleavage of A -THfluoroacetyl Groups with Aqueous Piperidine Typical Procedure " ... 

Breaking the DNA chain next to the pyrimidine nucleotides C and T is accomplished by treatment of DNA with hydrazine, H2NNH2, followed by heating with aqueous piperidine. Although no conditions have been found that are selective for cleavage next to T, a selective cleavage next to C can be accomplished by carrying out the hydrazine reaction in 5 M NaCl solution. 

RCO-H, using either aqueous piperidine at 90°C or copper sulphate and... 

The aziridinium salt (44 R = H) reacts with 2-chloroethanol to give the 1,4-oxazinium derivative (120) (Equation (57)) <76JOC390>. The dioxaspirononanedione (121) reacts with aqueous piperidine to give the mesoionic azoniaspirodecenone (17) <76JOC390>, obtained in better yield from the benzil (122) (Scheme 16). 

Reaction of 3,4-dimethylthiophene-1,1-dioxide with benzylthiolate at room temperature gives 3-benzylthiomethyl-4-methyl-2,5-dihydrothiophene-l,1-dioxide (208) in 86% yield. Again an exomethylene tautomer is implicated. A similar reaction takes place with iec-amines. With the 2,5-dimethyl isomer (202a), reaction with benzylthiolate is analogous to that with aqueous piperidine. 

Since solvolysis of X—PhPh2SiH in moist piperidine gives a good Hammett correlation, with positive rho, and isotope studies in Ph3SiH/ aqueous piperidine, and C2H5OH, H2O, KOH involving both solvent and... 

The in-formyl group is cleaved by weak bases such as aqueous piperidine or hydrazine. Its sensitivity to amines can pose some problem in mildly basic media it migrates to a-amino groups. On the other hand, the in-formyl group is indeed able to reduce the extent of alkylation, for instance tert.butylation that occurs during the removal of tert.butyl groups by acidolysis. Also, in N "-for-myl derivatives of tryptophan containing peptides less oxidation takes place in acidic media, a reaction that results in the formation of colored products. 

Obtained by selective demethylation of 2-hydroxy-3,4,5-tri-methoxybenzophenone with refluxing aqueous piperidine for 45-65 h [416],... 

Scission of the silicon-siUcon bond of disilanes is also achieved through the agency of aqueous or methanolic alkali, aqueous piperidine, and alkali in hexanol. All of these reactions can be considered as an attack of a basic or nucleophilic species and are represented generally as follows ... 

Compound C is relatively unreactive in comparison with octaphenyl-cyclotetrasilane and decaphenylcyclopentasilane. Thus, it does not react with iodine, rywi-tetrachloroethane, or refluxing nitrobenzene, nor does it react appreciably with alkali or aqueous piperidine. ... 

Depurination reaction with 0.13 M aqueous piperidine formate at pH 2.0, 20°C, and for 60 min. The depurination is followed by strand scission in the presence of piperidine. 

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