Alkene epoxidation catalysed by camphor-derived β-ketophosphonate complexes of molybdenum(VI)
摘要:
New beta-ketophosphonates (L) have been prepared from (R)- or (S)-camphor with various substituents on the phosphorus atom [EtO, (R)- or (S)-Bu(s)O, Ph or binaphthoxy] and reacted with [MoO2Cl2] to form complexes [MoO(2)Cl(2)L]. These complexes have been used to give highly active catalysts for epoxidation of alkenes by Bu(t)OOH. Very fast initial rates (ca. 400 catalyst turnovers in the first minute) gave way to much slower rates because the hemi-labile beta-ketophosphonate is displaced by a diol ligand. In the presence of molecular sieves, the fast initial stage of the reaction is extended and for styrene, which gives low conversions followed by degradation in the absence of molecular sieves, styrene oxide can be formed with 98% conversion and 94% selectivity. It is demonstrated that both the Bu(t)OOH and the catalyst bind to the molecular sieves. the latter with loss of the beta-ketophosphonate ligand.
Alkene epoxidation catalysed by camphor-derived β-ketophosphonate complexes of molybdenum(VI)
摘要:
New beta-ketophosphonates (L) have been prepared from (R)- or (S)-camphor with various substituents on the phosphorus atom [EtO, (R)- or (S)-Bu(s)O, Ph or binaphthoxy] and reacted with [MoO2Cl2] to form complexes [MoO(2)Cl(2)L]. These complexes have been used to give highly active catalysts for epoxidation of alkenes by Bu(t)OOH. Very fast initial rates (ca. 400 catalyst turnovers in the first minute) gave way to much slower rates because the hemi-labile beta-ketophosphonate is displaced by a diol ligand. In the presence of molecular sieves, the fast initial stage of the reaction is extended and for styrene, which gives low conversions followed by degradation in the absence of molecular sieves, styrene oxide can be formed with 98% conversion and 94% selectivity. It is demonstrated that both the Bu(t)OOH and the catalyst bind to the molecular sieves. the latter with loss of the beta-ketophosphonate ligand.
Simple phosphorus-31 NMR method for the determination of enantiomeric purity of alcohols not requiring any chiral auxiliary compounds
作者:Ben L. Feringa、Ab Smaardijk、Hans Wynberg
DOI:10.1021/ja00302a043
日期:1985.8
En utilisant PCl 3 comme agent de dimerisation les alcools sont convertis en phosphonates par une reaction rapide et quantitative. Application a la determination de la purete enantiomere de l'octanol-2
使用 PCl 3 comme agent de dimerisation les alcools sont convertis en phosphonates par une反应快速等。应用 a la 测定 de la purete enantiomere de l'octanol-2
Hulst, Ron; Vries, N. de Koen; Feringa, Ben L., Angewandte Chemie, 1992, vol. 104, # 8, p. 1089 - 1091