Asymmetric syntheses of the 1-hydroxymethyl-2-hydroxy substituted pyrrolizidines (−)-macronecine, (−)-petasinecine, (−)-1- epi -macronecine, (+)-1- epi -petasinecine and (+)-2- epi -rosmarinecine
作者:Marta Brambilla、Stephen G. Davies、Ai M. Fletcher、Paul M. Roberts、James E. Thomson
DOI:10.1016/j.tet.2016.09.047
日期:2016.11
Following this route, (−)-macronecine, (−)-petasinecine, (−)-1-epi-macronecine and (+)-1-epi-petasinecine were synthesised in 21, 14, 10 and 19% overall yield, respectively, in six steps or fewer from commercially available starting materials. An analogous strategy employing enantiopure tert-butyl (R,E)-4-(triethylsilyloxy)hepta-2,6-dienoate facilitated the asymmetricsynthesis of (+)-2-epi-rosmarinecine