Abstract: The invention relates to new racemic and optically active apovincaminic acid derivatives of the general formula (I) ##STR1## wherein A is hydroxyl, halogen or a group --O--(CH.sub.2).sub.n --OR.sup.1 or --OMe, in whichR.sup.1 is alkyl having from one to 6 carbon atoms,n is an integer between 2 and 6,Me is an alkali metal,R.sup.2 stands for an alkyl group having from one to 6 carbon atoms, which may be identical with or different from R.sup.1,and the hydrogen in the 3-position and the R.sup.2 group have an .alpha.,.alpha.- and/or .beta.,.beta.- or .alpha.,.beta.- and/or .beta.,.alpha.-configuration, and pharmaceutically acceptable acid addition salts thereof, which are pharmaceutically active, e.g. show antihypoxial activity or are potent peripheral vasodilators. Their preparation and pharmaceutical composition containing them are also within the scope of the invention.

Abstract: The invention relates to a new crystal modification of N-methyl-N'-{2-[(5-methylimidazol-4-yl)-methylthio]-ethyl}-N"-cyanoguanidi ne (cimetidine), a histamine H-2 receptor antagonist having the Formula (I) ##STR1## as well as to a process for preparing same. In the description, this new modification is named N-methyl-N'-{2-[(5-methylimidazol-4-yl)-methylthio]-ethyl}-N"-cyanoguanidi ne Z (cimetidine Z).

Abstract: A process is disclosed for the preparation of racemic cis or trans apovincaminic acid esters of the formula (I) ##STR1## and the corresponding optically active derivatives of the formulae (Ia) ##STR2## wherein R.sup.1 and R.sup.2 are identical or different alkyl groups having 1 to 6 carbon atoms. Apovincaminic acid alkyl esters are well-known vasodilating compounds.

Abstract: The invention relates to a new process for the preparation of apovincaminic acid esters. More particularly, the invention concerns a process for preparing racemic and optionally active vincaminic acid esters of the formula (I) ##STR1## in which R.sup.1 and R.sup.2 independently stand for alkyl having from one to 6 carbon atoms, and 14-epimers thereof.According to the invention an octahydroindolo[2,3-a]quinolizine-oxime ester of the formula (II) ##STR2## in which R.sup.1 and R.sup.2 have the same meaning as defined above, is reacted with an aqueous solution of sulfurous acid or a salt thereof at a temperature of 80.degree. to 110.degree. C. and the 14-epimeric mixture obtained is epimerized or separated in a known manner and if desired, the racemic vincaminic acid esters are resolved.

Abstract: The invention relates to a new process for the preparation of eburnamonine derivatives of the general Formula I ##STR1## (wherein R.sup.1 is an alkyl group having 1-6 carbon atoms) and optical and geometrical isomers thereof which comprises reacting a hydroxyimino-octahydro-indolo[2,3-a]quinolizine derivative of the general Formula II ##STR2## (wherein R.sup.1 is as stated above and R.sup.2 stands for an alkyl group having 1-6 carbon atoms being identical with or different from R.sup.1, or a hydrogen atom) or an acid addition salt thereof in an organic protic solvent or solvent mixture with an inorganic base, optionally under the addition of water or an aqueous mineral acid, at a temperature between 60.degree. C. and 200.degree. C.The compounds of the present invention are known drugs having blood pressure decreasing and cerebral vasodilatatory effect.

Abstract: The invention relates to a new enantioselective synthesis for the preparation of optically active 14-oxo-E-homo-eburnane derivatives of the formula (Ia) ##STR1## wherein R.sup.1 is alkyl having from 1 to 4 carbon atom. In the synthesis optically active 6-alkoxycarbonylhexahydroindoloquinolizinium salts are employed as starting materials, which contain a center of chirality at the site of attachment of the carboxyl group. This center of chirality preserves the optical activity of the optically active tryptophan ester from which this compound has been prepared until a new center of chirality is formed in the molecule in a configuration corresponding to the desired end product. The carboxyl group, which is not needed in the end product and only serves to preserving the optical activity can then be eliminated.Compounds of the formula (Ia) are known in the art and may be used in the synthesis of (+)-vincamine and (+)-apovincaminic acid ethylester.