The present invention relates to regioselective chemical and electrochemical processes for the preparation of an oxidized heterocyclic alpha-amino amide compounds. By applying specific catalysts or catalyst systems during chemical oxidation or by applying particular electrochemical oxidation conditions the present invention provides access to valuable alpha amino amide compounds, which are oxidized at the heterocyclic amino group by regioselective introduction of either a hydroxyl or a keto group. In a more particular embodiment, the present invention describes a chemical oxidation reaction, which advantageously is applicable in the enantioselective synthesis of valuable oxidized heterocyclic alpha-amino amide compounds, like levetiracetam, brivaracetam or the synthesis of piracetam. Another aspect of the present invention relates to a process for the electrochemical recycling of alkali perhalogenate oxidants as spent during said regioselective oxidation reactions of the invention. Still another aspect of the invention relates to the electrochemical preparation of perhalogenates.
2,6-Piperidinediones, I. Synthesis of the Racemates and the Enantiomers of 3,3-Disubstituted 2,6-Piperidinediones
作者:Joachim Knabe、Dirk Reischig
DOI:10.1002/ardp.19843170413
日期:——
The synthesis of the racemates and the enantiomers of the 3,3‐disubstituted 2,6‐piperidinediones 3a–3g is performed in three ways, depending on the C‐3 substituents. The 3‐cyclohexylpiperidinedione 3h is obtained as racemic and optically active compound by hydrogenation of the cyclohexenyl compound 3e with Pd/C. The N‐methylpiperidinediones 7a and 7b are obtained by methylation of 3a and 3b with CH2N2