کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5217899 | 1383310 | 2013 | 10 صفحه PDF | دانلود رایگان |

Chiral diether-mediated asymmetric aminolithiation of indolylpropenoate with lithium amide in toluene at â78 °C for 15 min gave, after aqueous ammonium chloride quench, the corresponding conjugate addition product with 97% ee in 89% yield. If hydrogen chloride in methanol was selected as a quencher, however, aminolithiation at â78 °C for 3 h gave the corresponding adduct with 97% ee in 54% yield, along with recovery of the starting enoate in 39% yield. Based on this finding of an incomplete and slow reaction at â78 °C, the aminolithiation conditions were optimized to be at â60 °C for 15 h and subsequent enolate trap with alkyl halide upon an addition of DMPU afforded the desired aminoalkylation product with 98% ee in 89% yield. Further approach toward total synthesis of (â)-kopsinine was carried out by examining asymmetric aminolithiation with N-hydroxyethylamine equivalent, one-pot piperidine formation, and Claisen condensation.
Journal: Tetrahedron - Volume 69, Issue 15, 15 April 2013, Pages 3264-3273