0000000000231085
AUTHOR
Johann Mathias
ELEKTROREDUKTIVE DIREKTDARSTELLUNG VON Ni(O)-, Pd(O)- UND Rh(O)-PHOSPHIN-KOMPLEXEN1
Abstract 1. Der Ni(O)-Komplex [Ni(PC2P)2] 1 mit zwei Ethylen-1,2-bis (diphenylphosphin)-Partnern (PC2P) als Ligand wird elektroreduktiv erhalten: (a) aus [Ni(PC2P)2Br2]; (b) aus [Ni(PC2P)Br2] + PC2P; (c) aus NiBr2 · 3H2O + 2PC2P. Die Ausbeuten liegen uber 90%. Nach Verfahren (b) entstehen auch Komplexe mit zwei unterschiedlichen Liganden, z.B. [Ni(PC2P) (PPh3)2] 4 [Ni(PC2P)(PC3P)] 5, [Ni(PC2P)(AsPh3)2], wenn man an Stelle von PC2P. PPh3. PC3P und AsPh3 einsetzt. (PC3P entspricht Trismethylen-1.3-bis (diphenylphosphin). Nach dem Direktverfahren, (c) ist Tetrakis(triphenylphosphinnickel(O) [Ni(PPh3)4] 6 in einer Ausbeute von 77% zuganglich. 2. [PD(PC2P)2] 7 entsteht elektroreduktiv nach Verfa…
Chemoselektive mono- und disilyletherbildung aus tertiären und sekundären silanen
Abstract Tertiary and secondary silanes are O-selective. With alcohols the corresponding silyl ethers are formed. Cesium fluoride/imidazole (CsF/Im) is a better activating system than CsF alone. Primary OH groups are silylated remarkably faster under CsF/Im activation than secondary OH groups. Tertiary alcohols do not react. Primary OH groups are selectively protected also in the presence of secondary OH groups by silanes with bulky ligands such as triisopropylsilane ((i-Pr) 3 SiH ( 4 )). Ketones are neither reduced to silyl ethers nor transformed to silylenol ethers under the conditions employed. Secondary silanes form monosilyl ethers by amine activation; with CsF the formation of disilyl…
Fluoreszierende silane als OH-selektive schutzgruppen
Abstract Fluorescent tertiary silanes are synthesized which, under cesium fluoride/ imidazole activation, discriminate between primary and secondary OH groups. Serine n-butylamide reacts with [5-dimethylamino(1-naphthyl)]dimethylsilane ( 1 ) and diisopropyl[5-dimethylamino(1-naphthyl)]silane ( 2 ) to form the silyl ethers (−)- l -3-[5-dimethylamino(1-naphthyl)]-dimethylsilyloxy]serine n-butylamid ( 14 ) and (−)- l -3-[diisopropyl[5-dimethylamino(1-naphthyl)]silyloxy]serine n-butylamid ( 15 ) exclusively. The silyl ethers are cleaved on treatment with H 2 F 2 , forming the corresponding fluorescent silyl fluorides. Absorption and fluorescence data as well as stability data for the hydrolysis…