This paperback is the conference documentation of the fifth Seminar on MODERN SYNTHETIC METHODS 1989. It is the aim of these triennial Interlaken-Seminars to provide a proper, concine and "ready for use" acceos to important and rapidly developing areas of synthetic organic chemistry. Usefu.l synthetic methods have to combine economic and ecological aspects. The search for such methods is a continuous scientific challenge. It implies a solid knowledge a~d updated information on current prospects in biochemistry, organic as well as inorganic chemiotry. The main themes of the 1989-Seminar are "Biotransformations in Organic Synthesis", "Enantioselective Catalyois with Metal Complexes" and "Aluminosilicates in Organic Synthesis". These topics have been chosen, since they reflect the enormous progress in experience and understanding of catalysis in organic syntheGis. This book if' the compilation of the contributions provided by the lecturers of the Seminar. The reviews are written by leading experts and describe not only the basic concepts, their application in oynthesis but also contain representative experimental procedures. The purpose of this volume is twofold. It should aid participants and students in following the lectures. The main reason, however, is to serve ao an updated guide for chemists interested in catalyois applied to organic synthesis.