Total Synthesis of (+)-Epilupinine via An Intramolecular Nitrile Oxide-Alkene Cycloaddition

Total synthesis of (+)-epilupinine was accomplished in nine steps and in 48% overall yield, in which INOC was used as the key step for the construction of the quinolizidine skeleton. We found that it was an extremely difficult task to prepare the key intermediates (<i>R</i>)-<i>N</i>-(3-nitropropyl)-2-vinylpiperidine or (<i>R</i>)-(2-vinylpiperid-1-yl)propanal by routine methods. Thus, by using Fukuyama’s oxime synthesis, a general method was developed for highly efficient conversion of 3-(<i>N</i>,<i>N</i>-dialkylamino)propanols into 3-(<i>N</i>,<i>N</i>-dialkylamino)propanal oximes without using the corresponding aldehydes.