Diastereo- and enantioselective syntheses of (−)-coniine, (−)-solenopsin A, (−)-solenopsis fugaz venom and (−)-xenovenine via deoxygenative decarboxylation of 2-carbonylsultam-substituted n-hydroxy-piperidines and -pyrrolidines
作者:Wolfgang Oppolzer、Christian G. Bochet、Eric Merifield
DOI:10.1016/0040-4039(94)88213-4
日期:1994.9
Heating cyclic 2-carbonylsultam-substituted N-hydroxylamines 4 with NaH yields sultam auxiliary 8 and imines 10, which are trapped in situ either by i-Bu2AlH or organocerium reagents to give enantiomerically pure 2-mono- or trans-2,6(2,5)-disubstituted piperidines (pyrrolidines) 11 or 12.
Herein, a method for the enantioselective reduction of unprotected 2-alkylpyridines is reported for the first time. By using pinacolborane and an amide as reducing agents, a large number of 2-alkylpiperidines were synthesized with high yields and excellent enantioselectivities via a cascade process involving 1,4-hydroboration and subsequent transfer hydrogenation. The resulting products can be easily
Short Enantioselective Total Syntheses of the Piperidine Alkaloids (<i>S</i>)-Coniine and (2<i>R</i>,6<i>R</i>)-<i>trans</i>-Solenopsin A via Catalytic Asymmetric Imine Hydrosilylation
作者:Matthew T. Reding、Stephen L. Buchwald
DOI:10.1021/jo980808q
日期:1998.9.1
The enantioselectivesyntheses of (S)-coniine and (2R,6R)-trans-solenopsin A are reported. The key step in both syntheses is the catalytic asymmetric hydrosilylation of a cyclic imine.