17 páginas, 12 figuras, 4 esquemas, 7 tablas.-- Supporting information for this article is available on the WWW under http://www.wiley-vch.de/home/chemistry/ or from the author., The development of effective strategies for the synthesis of phosphatidylinositol precursors such as that which contains the trisaccharide 1, the study of their conformational features and dynamics, and the investigation of their biological properties may result in a better understanding of the mechanism of signal transduction of insulin and a number of growth factors. This new pathway of intracellular signalling has been postulated to proceed through uncharacterized inositolphosphoglycan mediators containing substructures such as 1., Thanks are given to DGICYT (Spain) for financial support (grants no. PB93-0127-C02-01, PB93-0125H and PB93-0098). H. D. is grateful to the Deutsche Forschungsgemeinschaft (DFG) and the European Union (HCM Programme; CARENET-1 Network) for a postdoctoral fellowships. J.-F. E. thanks M.E.C. for a FPU Fellowship. Y. L. is supported by a MEC-CSIC contract.