| abstract |
D-(+)-Biotin can be prepared from optically active hydantoins of the formula I ##STR1## wherein R 1 , R 2 , R 3 , X and Y have the meaning given in patent claim 1, in a simple, stereospecific manner. n Furthermore bicyclic nitriles of the formula XI ##STR2## wherein R 1 , R 2 , R 3 , X and Y have the meaning given represent precious intermediate products and educts of a multitude of possibilities to synthesize optically active D-(+)-biotin. |