Oxidation of chiral non-racemic pyridinium salts to enantiopure 2-pyridone and 3-alkyl-2-pyridones
摘要:
Oxidation of chiral non-racemic pyridinium salt 1a and 3-alkyl pyridinium salts 1b and 1c with potassium ferricyanide in an alkaline medium provides a short and practical access to enantiomerically pure 2-pyridone (2a) and 3-alkyl-2-pyridones (2b and 2c) in high yields and very good regioselectivity from derivatives 1(b-c). (C) 1998 Elsevier Science Ltd. All rights reserved.
[GRAPHICS]The phenylglycinol-derived 2-pyridone 1 undergoes m-CPBA oxidation steroselectively leading to the chiral nonracemic unsaturated bicyclic hydroxylactam 2, from which the enantioselective synthesis of (3R,5R)-3,4,5-trihydroxypiperidine (16) and the formal synthesis of the azasugar epiisofagomine are described. The enantioselective synthesis of (S)-N-Boc-3-hydroxypiperidine and (3R,4S)-3,4-dihydroxyplperidlne is also reported.
Oxidation and Aromatization of the Enantiopure Piperidine Derived from (R)-(-)-2-Phenylglycinol to (1’R)-(-)-1-(2’-Hydroxy-1’-phenylethyl)-1H-pyridin-2-one
作者:Jorge R. Juárez、Alejandro Castro、Oscar Romero、Joel L. Terán、Dino Gnecco、Laura Orea、Angel Mendoza
DOI:10.3987/com-13-12911
日期:——
An efficient oxidation of enantiopure piperidine 1 with bromine in acetic acid to generate the corresponding enantiopure (R)-3,3-dibromo-1-(2'-hydroxy-1'-phenylethyl)piperidin-2-one 2 is described. Then, aromatization of compound 2 to give enantiopure pyridin-2-one 3 in 71% overall yield is presented.