An Efficient Synthesis of 3-Phosphorylated 4(1H)-Pyridones and 4-Chloropyridines fromb-Enaminophosphonates
作者:Francisco Palacios、Ana Ma Ochoa de Retana、Julen Oyarzabal
DOI:10.3987/com-97-s(n)70
日期:——
An easy and efficient synthesis of 4(1H)-pyridones (1) substituted with a phosphate group in the 3-position is described. The key step is an addition of beta-enaminophosphonates (2) to acylketene (3) generated either from diketene (4) or from the "diketene-acetone adduct", 2,2,6-trimethyl-4H-1,3-dioxin-4-one (5), Subsequent treatment of 4(1H)-pyridones with phosphorus oxychloride in the presence of dimethylformamide afforded the substituted 4-chloropyridine (6).
Rhodium-catalyzed asymmetric hydrogenation of unprotected β-enamine phosphonates
We have successfully developed a strategy for the first time for the enantioselective Rh-TaniaPhos catalyzed asymmetric hydrogenation of unprotected β-enamine phosphonates to free β-amino phosphonates directly with good enantioselectivities (80%–86% ee) and high conversions (>99% conversion). The resulting chiral free β-amino phosphonates and their derivatives are important intermediates in biochemistry
Asymmetric Hydrogenation of α- and β-Enamido Phosphonates: Rhodium(I)/Monodentate Phosphoramidite Catalyst
作者:Jinzhu Zhang、Yang Li、Zheng Wang、Kuiling Ding
DOI:10.1002/anie.201104912
日期:2011.12.2
High efficiency and enantioselectivity have been achieved in the RhI‐catalyzed asymmetrichydrogenation of α‐ and β‐enamido phosphonates using a monophosphoramidite as the chiral ligand (see scheme; cod=1,5‐cyclooctadiene), thus affording the optically active amino phosphonates with a turnover frequency of up to 1800 h−1 and high ee values.
使用单亚磷酰胺作为手性配体,在Rh I催化的α-和β-氨基膦酸酯的不对称氢化中实现了高效率和对映选择性(参见方案; cod = 1,5-环辛二烯),从而提供了光学活性的氨基膦酸酯具有高达1800 h -1的周转频率和高ee 值。