Alkyl Substituent Effects on Pipecolyl Amide Isomer Equilibrium: Efficient Methodology for Synthesizing Enantiopure 6-Alkylpipecolic Acids and Conformational Analysis of Their <i>N</i>-Acetyl <i>N</i>‘-Methylamides
作者:Martin E. Swarbrick、Francis Gosselin、William D. Lubell
DOI:10.1021/jo982181h
日期:1999.3.1
analysis by proton NMR spectroscopy and coalescence experiments. The presence of the tert-butyl substituent augmented the population of the amide cis-isomer and lowered the barrier for pipecolyl amide isomerization in water. Compared with the results from our previous examination of N-acetyl-5-tert-butylproline N'-methylamides (Beausoleil, E.; Lubell, W. D. J. Am. Chem. Soc. 1996, 118, 12902), the consequences
Total Synthesis of (+-)-Monomorine I and (+-)-Indolizidine 195B by an Aza-[2,3]-Wittig Rearrangement of a Vinylaziridine.
作者:Peter Somfai、Tomas Jarevång、Ulf M. Lindström、Anette Svensson、M. Hanfland、E. Dooryhee
DOI:10.3891/acta.chem.scand.51-1024
日期:——
A novel synthesis of (+/-)-monomorine I (1) and (+/-)-indolizidine 195B (2) is described in which the key step is the highly efficient aza-[2,3]-Wittigrearrangement of vinylaziridine 12 into tetrahydropyridine 13. Functional group manipulation then gave ketone 16 which could be converted into the target alkaloids by reductive amination (1:2 1.5:1).