Toxic piperidine alkaloids from pine (Pinus) and spruce (Picea) trees. New structures and a biosynthetic hypothesis
摘要:
A series of 2,6-disubstituted piperidine alkaloids have been isolated from several Pinus (pine) and Picea (spruce) species and characterized structurally. The pines appear to contain only cis-disubstituted piperidines, while the spruces contain both cis- and trans-disubstituted piperidines. The structural relationships among the alkaloids suggest a plausible biosynthetic scheme and a reason why previous attempts to elucidate the biosynthesis of pinidine failed beyond establishing its polyketide origin. A mixture of alkaloids from needles of Pinus ponderosa proved to be highly teratogenic. The alkaloids might therefore be involved in so-called pine needle abortion which occurs in pregnant range cows which feed on Ponderosa pine needles.
A Diastereoselective Intramolecular Hydroamination Approach to the Syntheses of (+)-, (±)-, and (−)-Pinidinol
摘要:
A diastereoselective, lanthanocene-catalyzed, intramolecular hydroamination reaction was applied to the preparation of 2,6-disubstituted piperidines. Various metal/ligand arrays in the catalysts were examined using a model substrate to allow optimization of the diastereoselectivity. It was determined that the relationship between metal size and ligand bulk plays an integral role in the transformation. The complex Cp*2NdCH(TMS)(2) converted 2-substituted 8-nonen-4-amines to 2,6-disubsituted piperidines with greater than 100:1 selectivity for the formation of the cis isomer. A short synthesis of pinidinol, an alkaloid isolated from various pine and spruce species, was then carried out to exploit this stereoselective reaction.
A short step synthesis of the bioactive piperidinealkaloid (-)-pinidinol was achieved using a cross metathesis and a reductive amination as the key steps.
syn-1,5-diol stereodivergently, which have been converted by aminocyclization into trans- and cis-2,6-disubstituted piperidines (trans- and cis-12), respectively. The first totalsynthesis of (+)-9-epi-6-epipinidinol (2) and (−)-pinidinol (3) has been achieved from trans- and cis-12.
Diastereocontrolled reduction of cyclic β-enaminones. A new diastereoselective route to 2,6-disubstituted piperidines
作者:Stéphanie Fréville、Philippe Delbecq、Vu Moc Thuy、Huguette Petit、Jean Pierre Célérier、Gérard Lhommet
DOI:10.1016/s0040-4039(01)00770-5
日期:2001.7
A new diastereoselective synthesis of 2,6-disubstituted piperidinic alkaloids is presented. Three natural compounds, the (−)-pinidinone 1a, the (+)-dihydropinidine 1b and the (−)-pinidinol 1c were prepared from optically pure (6R)-6-methylpiperidin-2-one 2. This method is based on the chemo- and diastereocontrolled reductions of an exocyclic β-enamino ketone.
A Diastereoselective Intramolecular Hydroamination Approach to the Syntheses of (+)-, (±)-, and (−)-Pinidinol
作者:Gary A. Molander、Eric D. Dowdy、Shawn K. Pack
DOI:10.1021/jo015603n
日期:2001.6.1
A diastereoselective, lanthanocene-catalyzed, intramolecular hydroamination reaction was applied to the preparation of 2,6-disubstituted piperidines. Various metal/ligand arrays in the catalysts were examined using a model substrate to allow optimization of the diastereoselectivity. It was determined that the relationship between metal size and ligand bulk plays an integral role in the transformation. The complex Cp*2NdCH(TMS)(2) converted 2-substituted 8-nonen-4-amines to 2,6-disubsituted piperidines with greater than 100:1 selectivity for the formation of the cis isomer. A short synthesis of pinidinol, an alkaloid isolated from various pine and spruce species, was then carried out to exploit this stereoselective reaction.
Toxic piperidine alkaloids from pine (Pinus) and spruce (Picea) trees. New structures and a biosynthetic hypothesis
作者:Jeanne N. Tawara、Andrei Blokhin、Tommaso A. Foderaro、Frank R. Stermitz、Hakon Hope
DOI:10.1021/jo00070a014
日期:1993.8
A series of 2,6-disubstituted piperidine alkaloids have been isolated from several Pinus (pine) and Picea (spruce) species and characterized structurally. The pines appear to contain only cis-disubstituted piperidines, while the spruces contain both cis- and trans-disubstituted piperidines. The structural relationships among the alkaloids suggest a plausible biosynthetic scheme and a reason why previous attempts to elucidate the biosynthesis of pinidine failed beyond establishing its polyketide origin. A mixture of alkaloids from needles of Pinus ponderosa proved to be highly teratogenic. The alkaloids might therefore be involved in so-called pine needle abortion which occurs in pregnant range cows which feed on Ponderosa pine needles.