Organo-phosphorus compounds S 0080 Diastereoselective Cycloalkylation of Phosphoryl and Thiophosphoryl Acetonitriles by α,ψ-Dihalogenalkanes under Phase Transfer Catalysis Conditions. -Interaction of phosphoryl-and thiophosphoryl-acetonitriles (I), (IV), and (VII) with dihaloalkanes (II) leads to ring formation affording cycloalkylation products (III), (V), (VI), and (VIII) as trans isomers. The configuration of the asymmetric cyclic carbon atoms remains identical independent of the substituents at the phosphorus atom and of PTC-system in use. An additional asymmetric phosphorus atom in substrate (IV) gives rise to the formation of trans isomers (V) and (VI) as mixture of diastereomers, differing in the configuration of the phosphorus atom. -(ODINETS*, I. L.; VINOGRADOVA, N. M.; LYSSENKO, K. A.; PETROVSKII, P. V.; MASTRYUKOVA, T. A.; ROESCHENTHALER, G.--.; Heteroat. Chem. 17 (2006) 1, 13-21; Nesmeyanov Inst. Organoelem. Compd., Russ. Acad. Sci., Moscow 117813, Russia; Eng.) -H. Hoennerscheid 24-171