PUB - Publikationen an der Universität Bielefeld

The versatile reactivity of the geminal oxygen-bridged frustrated Lewis pair (FLP) Bis(2)Ga-O-PtBu2 (Bis = CH(SiMe3)(2); GaOP) is presented towards a series of CvO double bonds, strained oxygen-containing rings, alkynes plus alkenes and a C-Cl bond. By adding benzaldehyde, cyclopentanone (CP), gamma-butyrolactone (GBL) or ethylene carbonate (EC), classical 1,2-adducts are formed. The reversibility of the GaOP EC adduct stands out, enabling a splitting of EC after several days or when heated to 70 degrees C, resulting in FLP adducts of CO2 and ethylene oxide (EO). The latter consists of a six-membered ring and is obtained via a ring-opening reaction, as verified by a further reaction involving the similar propylene oxide (PO). The GaOP GBL adduct is further converted, with two adduct molecules combining into a 2: 1 FLP adduct in a Claisen-type addition and ring-opening. Tests towards various acetylene containing species revealed that the ratio of deprotonation to ring-closure product can be adjusted. While PhCuCH is almost exclusively bound as the deprotonation product, for Me3SiCuCH, the ring-closure product also forms. In the reaction with benzyl chloride, Bis(2)(Cl)Ga-O-P(Bn)tBu2 is formed by a C-Cl bond activation.