Chelating Bis(thiophosphinic amidate)s as Versatile Supporting Ligands for the Group 3 Metals. An Application to the Synthesis of Highly Active Catalysts for Intramolecular Alkene Hydroamination
Bis(thiophosphinic amidate) complexes (i.e., 1) of representative group 3 and lanthanide metals have been quantiatively prepared in situ from the corresponding thiophosphinic amides and Ln[N(TMS)2]3. These unusual pentacoordinate complexes exhibit very high activity as catalysts for intramolecular alkene hydroamination.
Mild acetalisation of mono and dicarbonyl compounds catalysed by titanium tetrachloride. Facile synthesis of β-keto enol ethers
作者:Angelo Clerici、Nadia Pastori、Ombretta Porta
DOI:10.1016/s0040-4020(00)01001-2
日期:2001.1
The use of TiCl4, as a catalyst for the acetalisation, at room temperature, of carbonyl compounds is reported. Cyclic ketones and cyclic 1,4-diketones easily afford dimethyl acetals, but cyclic 1,3-diketones give beta -keto enol ethers. Additionally, aryl ketones and acyclic ketones failed to react. beta -keto aldehydes can be monoprotected either as beta -keto enol ethers or beta -keto dimethyl acetals depending on the reaction time and catalyst amount. Some mechanistic features are accounted for. (C) 2000 Elsevier Science Ltd. All rights reserved.
Electronic spectra of .alpha.,.beta.-unsaturated carbonyl compounds. I. An evaluation of increments characteristic of changes in configuration (cis/trans) and conformation (s-cis/s-trans) based on direct observation of the isomerization of enamino aldehydes and ketones