Synthesis of vinca alkaloids and related compounds. Part 84. Sulfonamide derivatives of some vinca alkaloids with cardiovascular activity

(+)-Vincamine (1) and (+)-vinpocetine (2) were chlorosulfonylated and the resulting sulfonyl chloride isomers (3-6) were transformed into sulfonamides (7-10). The ester group of sulfonamides was modified by selective hydrolysis and transesterification. Apovincaminol derivatives (14-16) were also prepared by reduction. In addition to the known cerebrovascular effects of the unsubstituted compounds (1,2) sulfonamides also show a significant peripheral vasodilator effect.

Chemistry of indoles carrying a basic function, Part 3. Synthesis of spiro[cyclopropane-1,3'[3H]indol]-2'(1'H)-ones with antihypoxic effects

Hydroxyindolones (1-6, 15-16) were transformed into isatinylidenes (7, 9-13, 17-19) by dehydration with 4-toluenesulfonic acid. The dimer-type compounds (14, 20) were also isolated in a few cases. The obtained isatinylidenes were transformed into 3-spiro-cyclopropane-oxindoles (21-32) with dimethyloxosulfonium methylide. Compound 22 shows protective effects against hypobaric hypoxia and triethyltin induced brain edema.

Estimation of impurity profiles of drugs and related materials Part 15. Identification of minor impurities in cimetidine

Besides several known impurities in cimetidine, two additional compounds at levels below 0.1% were detected by ion-pair reversed-phase high-performance liquid chromatography (HPLC). The impurities were isolated from crude cimetidine using normal-phase preparative HPLC. 1H and 13C NMR and mass spectrometric investigations revealed the structures of the impurities to be 2,5-bis[(N'-cyano-N"-methyl)guanidinoethylthiomethyl]-4-methylimid azole (VII) and 1,8-bis[(N'-cyano-N"-methyl)guanidino]-3,6-dithiaoctane (VIII). These structures were verified by synthesis of the impurities and comparison of the spectra and chromatographic (HPLC and TLC) retention data of the isolated and synthesized materials.

Synthesis of Vinca Alkaloids and Related Compounds. 79. An Intriguing Retro Diels-Alder Reaction(1)

The dimerization products of criocerine (1) are different (2 or 3) depending on whether the reaction is carried out in acetic acid or trifluoroacetic acid. The highly strained product 3 rearranges spontaneously through a retro Diels-Alder reaction. All structures involved were thoroughly investigated by NMR spectroscopic methods.

Inhibitors of lipid peroxidation among new pyrimido[1',6':1,2]pyrido[3,4-b]indoles

A series of potent inhibitors of NADPH- and Fe(2+)-dependent lipid peroxidation has been found among new pyrimido[1'6':1,2]pyrido[3,4-b]indole derivatives. According to preliminary structure-activity relationship analysis the saturated pyrimidine moiety was responsible for this effect. Some members of this family were effective in a bilateral carotid occlusion model in mice, and some derivatives showed protective effect in a mouse head injury model.

Structural elucidation of two novel ergot alkaloid impurities in alpha-ergokryptine and bromokryptine

Two novel natural derivatives (2 and 3) of the ergot alkaloid alpha-ergokryptine (1), as well as their synthetically brominated analogues (5 and 6) were isolated and identified by NMR and MS methods. Compounds 2 and 5 contain what appears to be a so far unknown natural amino acid building block. Complete 1H and 13C NMR assignments are given for compounds 1-6.