Biomedical subjects

H Möhrle

Publications and source records attributed to H Möhrle.

At least 19 recordsLinked to original sources

PubMed2005

[Reactions of N-quaternary 1-phenyl-3,4-dihydroisoquinolinium compounds with nucleophiles--products and their isomerism--part 2].

A series of substituted 1-phenyl-3,4-dihydroisoquinolinium compounds was treated with O-, C- and N-nucleophilic agents in order to study ring-chain isomerism of the products. With methanolate carbinolamine ethers and with cyanide pseudocyanides as cyclic species resulted from these iminium salts. Electronic and steric differently substituted dihydroisoquinoline compounds reacted with hydroxylamine under ring opening generally to amine oximes predominantly in their Z-configuration. A cyclic isomer substituted with a hydroxylamine group--also in equilibrium in solution--could be excluded. With O-methylhydroxylamine a similar reaction gave rise to amine oxime methyl ethers only. 4-Phenylsemicarbazide and 4-nitrophenylhydrazine in pyridine produced the ring opened hydrazone derivatives.

Chemical Phenomena↗

PubMed2003

[Reactions of N-quaternary 1-phenyl-3,4-dihydroisoquinolinium compounds with nucleophiles - products and their isomerism - part 1].

Variously substituted 1-phenyl-3,4-dihydroisoquinolinium compounds were prepared, in order to study their reactions with hydroxide ions concerning ring-chain isomerism of their products. Thereby was observed a dependence on the electrophilic properties of C-1 for forming the pseudo-bases and a ring opening tendency to the amino ketones by electron-withdrawing substituents at the nitrogen atom. Moreover steric effects caused by voluminous substituents in 1- and 2-positions also importantly affected the isomeric distribution. So the N-ethyl derivatives showed an enhanced dissociation of the hemiaminal to the quaternary iminium base. From a solution of the dihydroisoquinolinium salt 35 in [D6]DMSO after addition of NaOD until pH 10 resulted an equilibrium of the quaternary iminium base 36q, the pseudo-base 36a and the amino ketone 36b. These species were detected and assigned by NMR measurements.

Dimethyl Sulfoxide↗

PubMed2001

[Ring cleavage of N-arylpyridinium salts by nucleophiles--regioselectivity and stereochemistry of the products. 1].

The N-arylpyridinium salts 1, 5 und 10 generate with hydroxylamine a ring cleavage to the E/Z-oximes of the (2E,4E)-5-aminopentadienals 2, 6 und 11. With the 3-methylpyridinium derivative 12 the described regiospecifity of the reaction with nucleophiles is disproved. The attack by hydroxylamine is realized to a nearly equal degree at C-2 and C-6. As 2-methyl substituted products the E-oximes of (2E,4E)- and (2Z,4E)-5-aminopentadienal result, while as 4-methyl substituted products the E/Z-oximes of (2E,4E)-5-aminopentadienal are generated. Just so with the hydroxide ion as nucleophile from 12--in contrast to the literature--both position isomer 5-aminopentadienals are formed. They were characterized as 15 and 16. The quaternized product of nicotine 22 shows ring opening with hydroxide ion, not at C-2 as described formerly, but only at 6-position and gives rise to the 4-(N-methylpyrrolidinyl) substituted 5-aminopentadienal 23. By hydroxylamine only the E/Z-oxime mixture of the 4-substituted 5-aminopentadienal 25 is formed, which can be dehydrated to the nitrile 27.

Dimethyl Sulfoxide↗

PubMed2001

[Ring cleavage of N-arylpyridinium salts by nucleophiles--regioselectivity and stereochemistry of the products. 2].

The reaction of quaternary 3-pyridinecarboxamide compounds 2, 7 and 14 with alkali does not--contrary to literature--result in regiospecific ring opening, but yields mixtures of position isomer penta-2,4-dienal derivatives. With increasing steric hindrance by the 3-substituent, the hydroxide ion prefers the attack at 6-position. Usually products with all trans configuration are obtained. Only the 2-substituted aldehydes from 2 and 14 additionally occur in the 2,3-cis configuration as 5b and 21b, explainable by a hydrogen bond between the formyl and carbamoyl group. Surprisingly the "ring opened" 5-aminopenta-2,4-dienals 5 and 6 resp. 21 and 22 in acetone solution show an equilibrium of the positional isomers in each case, which must be generated by recyclization via the intermediates 24 resp. 25. With hydroxylamine 2, 7 and 14 only react to the 4-substituted pentadienal derivatives, which represent E,Z oxime mixtures. This is proved by dehydration to uniform nitriles and the synthesis from the corresponding aldehydes by oximation.

Aldehydes↗

PubMed2001

[Ring cleavage of N-methoxypyridinium salts by amines].

The 3- and 4-cyano-1-methoxypyridinium salts 1 and 2 reacted with primary and secondary, aliphatic and aromatic amines via ring cleavage to the 5-aminopenta-2,4-dienaloxime ethers 3-10, which were examined concerning their stereochemistry. Contrary to literature no uniform all-trans type products resulted, but the ring opened compounds 3, 4, 7 and 8 contained a cis double bond due to the initial cyclic compound. Partially the corresponding configuration isomers differed only slightly in the energy contents and according to the solvent an equilibrium was observed. Therefore the configuration of the products seems to depend sensitively on the reaction parameters.

Amines↗

PubMed1985

[Thin-layer densitometric determination of clotiazepam in tablets and blood plasma].

Quantitative determination of 7-ethyl-5-(2-chlorophenyl)-1-methyl-1,3-dihydro-2H-thieno[2,3-e]1, 4-diazepin-2-one (clotiazepam, Trecalmo) as pure substance and after extraction from tablets can be carried out by high performance thin-layer densitometry in absorbance at 243 nm. Detection limit was 10 ng/spot, and inaccuracy +/- 1.8% in the microgram range. For determination of clotiazepam in blood plasma, a more sensitive method was developed by fluorodensitometry above 460 nm after excitation at 313 nm. Analytical parameters are: detection limit 2.5 ng/ml, inaccuracy between 25 and 300 ng/ml +/- 5%, and imprecision at a concentration of 100 ng/ml +/- 5%. Plasma level determination up to 12 samples can be achieved in about 5 h. Thus, for determination of only a few samples, the HPTLC method is less time-consuming than the gas chromatographic assay.

Animals↗

PubMed1985