Abstract: Binuclear iridium (I) phosphine complexes of the general formula: ##STR1## in which X is fluorine, chlorine, bromine or iodine, and ##STR2## is in each case a chiral bidentate diphosphine ligand. The complexes are particularly suitable as catalysts for the inter- or intramolecular asymmetric hydroamination of prochiral olefins.

Abstract: A process for the asymmetric hydrogenation of the furoimidazole derivatives of the general formula: ##STR1## wherein R.sub.1 is a protective group, which is cleavable in a known way, and R.sub.2 is hydrogen or a protective group, which is cleavable in a known way, with hydrogen in the presence of a homogeneous catalyst to the corresponding diastereomeric tetrahydrofuroimidazole derivatives of the general formula: ##STR2## The tetrahydrofuroimidazole derivatives of the general formula II are intermediate products for the production of vitamin (+) biotin.

Abstract: A process for the preparation of carboxamides of nitrogen-containing aromatic heterocyclic compounds from the corresponding N-heterocyclic compounds by reaction thereof with formamide in the presence of peroxodisulfuric acid or a peroxodisulfate.

Abstract: A process for the asymmetric hydrogenation of the furoimidazole derivatives of the general formula: ##STR1## wherein R.sub.1 is a protective group, which is cleavable in a known way, and R.sub.2 is hydrogen or a protective group, which is cleavable in a known way, with hydrogen in the presence of a homogeneous catalyst to the corresponding diastereomeric tetrahydrofuroimidazole derivatives of the general formula: ##STR2## The tetrahydrofuroimidazole derivatives of the general formula II are intermediate products for the production of vitamin (+) biotin.

Abstract: A process for preparing imidazopyridine derivatives of the general formula: ##STR1## wherein R.sub.1 is hydrogen or an alkyl group, and R.sub.2, R.sub.3 and R.sub.4 are identical or different and are hydrogen, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or a halogen atom. In this process, a 2-amino-3-nitropyridine is hydrogenated in the presence of a hydrogenation catalyst and the hydrogenation product is condensed with a carboxylic acid simultaneously present in the reaction mixture to give the end product. The imidazopyridine derivatives are intermediates for the preparation of angiotensin II antagonists.

Abstract: A process for the asymmetric hydrogenation of furoimidazole derivatives of the general formula: ##STR1## wherein R.sub.1 is a protective group and R.sub.2 is hydrogen or a protective group, with hydrogen in the presence of a homogeneous catalyst to give the corresponding diastereomeric dihydrofuroimidazole derivatives of the general formula: ##STR2## The dihydrofuroimidazole derivatives of the general formula II are intermediates for the preparation of the vitamin (+)-biotin.

Abstract: A process for the asymmetric hydrogenation of furoimidazole derivatives of the general formula: ##STR1## with hydrogen in the presence of a homogeneous catalyst to give the corresponding diastereomeric dihydrofuroimidazole derivatives of the general formula: ##STR2## R.sub.1 and R.sub.2 are protective groups, although R.sub.2 can be hydrogen. The dihydrofuroimidazole derivatives of the general formula II are intermediates for the preparation of (+)-biotin.

Abstract: 3-Oxocarboxylic acid esters are produced by acylation of the magnesium enolates of acetoacetic acid esters with carboxylic acid chlorides and cleavage of the acetyl group from the acylacetoacetic acid esters formed as the intermediate product. The yields and purity of the products are considerably improved by adding a tertiary amine during the acylation.

Abstract: Process for the preparation of 1,3-substituted tetrahydro-1H-thieno-[3,4-d]-imidazol-2(3H)-on-4-ylidene pentanoic acid esters which are intermediate products for the production of the pharmaceutic active substance (+)-biotin.

Abstract: Process for the preparation of 1,3-substituted tetrahydro-1H-thieno[3,4-d]-imidazol-2(3H)-on-4-ylidene pentanoic acid esters which are intermediate products for the production of the pharmaceutic active substance (+)-biotin.