Cobalt(II)-Catalyzed Intermolecular Diels−Alder Reaction of Piperine
作者:Kun Wei、Wei Li、Kazuo Koike、Tamotsu Nikaido
DOI:10.1021/ol050689i
日期:2005.7.1
[reaction: see text] An intermolecular cobalt-phosphine-catalyzed Diels-Alder reaction of piperine is described. The dimerization of piperine in the presence of cobalt-phosphine complexes gave much better yields than that in the presence of only cobalt, which, combined with the result under the purely thermal conditions, indicates that addition of phosphine ligands changes the inhibition of cobalt to
Fifteen novel dimeric amide alkaloids possessing a cyclohexene ring, nigramides A−O (1−15), as well as four novel dimeric amide alkaloids possessing a cyclobutane ring, nigramides P−S (17−20), have been isolated from the roots of Pipernigrum. Their structures were elucidated on the basis of their spectroscopic data. The biosynthestic hypothesis of nigramides A−O (1−15) was proposed by an intermolecular