Fixation of reaction partners at appropriate distances from one another is a structural prerequisite for vectorial reactions and reaction sequences. In biological systems (e. g. the photosynthetically active thylakoid membrane or membrane receptors) the positions of the reaction centers are fixed by membrane-protein complexes, but little is known about the structure of these complexes. Ordered reactive systems in synthetic vesicle membranes were first obtained by employing amphiphiles with reactive head groups as building units, by regioselective incorporation of foreign molecules into the membrane, by alignment of bolaamphiphiles with two head groups of differing solubility or size, and by the formation of domains. Chiral superstructures have also been observed in membranes, and the first stereoselective reactions have been performed in vesicle membranes. The report concludes with a brief discussion of membranes constructed from non-amphiphilic building blocks and problems which still have to be solved.
Es wird die Darstellung verschiedener Steroide in optisch reiner Form beschrieben. Als Ausgangs‐substanz für alle Synthesen wird zunächst aus 6‐Methoxy‐α‐tetralon eine tricyclische Verbindung hergestellt, die wohl den fünfgliedrigen D‐Ring, nicht aber die angulare 19‐Methyl‐Gruppe besitzt. Charakteristisch für die neue Synthese ist die frühzeitige Racemat‐Spaltung einer Carbonsäure und die Vorbereitung des A‐Ringes durch Kondensation mit 1.3‐Dichlor‐buten‐(2). Das Kondensations‐produkt besitzt die anti‐trans‐Konfiguration der natürlichen Steroide, es erlaubt die Herstellung sowohl von nor‐Derivaten als auch—durch Einführung der 19β‐Methyl‐Gruppe— die Synthese natürlicher Steroide (Östradiol, Adrenosteron, Cortison).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.