Regioselective Endocyclic Oxidation of Enantiopure 3‐Alkylpiperidines: Synthesis of (3<i>S</i>,5<i>S</i>)‐(‐)‐3‐Ethyl‐5‐Methylpiperidine
作者:Alejandro Castro、Jorge Juárez、Dino Gnecco、Joel L. Terán、Laura Orea,、Sylvain Bernès
DOI:10.1080/00397910500466454
日期:2006.3.1
An efficient regioselective endocyclic oxidation of enantiopure 3-alkylpiperidines 1( a-c) with bromine in acetic acid to generate the corresponding 5-alkylpiperidin-2-ones 3(a-c) as main product is described. In addition, starting from 3a or 3b, the synthesis of (3S,5S)-(-)-3-ethyl-5-methylpiperidine 6 (.) HCl was achieved. Finally, the X-ray single-crystal analysis of compound 4 is reported.
Enantioselective syntheses of the indole alkaloid (+)-R-decarbomethoxytetrahydrosecodine and its enantiomer
The alkaloid (+)-R-decarbomethoxytetrahydrosecodine (+)-1 has been synthesized by alkylation of (R)-3-ethylpiperidine with 3-(2-bromoethyl)-2-ethylindole (7). The required enantiopure piperidine was prepared by alkylation of the chiral non-racemic oxazolopiperidone (+)-trans-8 followed by reduction of the lactam carbonyl group and removal of the chiral auxiliary, whereas tryptophyl bromide 7 was obtained