The stereodifferentiating potential of arabinosyl aldimines was utilized in stereoselective syntheses of 2-substituted dehydropiperidinones and their further transformation to 2,6-cis-substituted piperidinones. The absolute configuration was proven by X-ray analysis and by the synthesis of the enantiomerically pure alkaloid (+)-dihydropinidine. The presented method offers the possibility to synthesize
阿拉伯糖醛亚胺的立体分化潜力可用于立体选择性合成 2-取代脱氢哌啶酮及其向 2,6-顺式取代哌啶酮的进一步转化。通过 X 射线分析和对映体纯生物碱 (+)-二氢吡啶的合成证明了绝对构型。所提出的方法提供了合成哌啶衍生物对映异构体的可能性,这些衍生物是通过应用相应的半乳糖胺辅助剂获得的。
Regio- and Stereoselective Monoamination of Diketones without Protecting Groups
作者:Robert C. Simon、Barbara Grischek、Ferdinand Zepeck、Andreas Steinreiber、Ferdinand Belaj、Wolfgang Kroutil
DOI:10.1002/anie.201202375
日期:2012.7.2
Hitting the right target: Differentiation between two keto moieties was accomplished by a regio‐ and enantioselective bioamination employing ω‐transaminases. Using 1,5‐diketones as substrates gave access to the opticallypure 2,6‐disubstituted piperidine scaffold. The approach allowed the shortest synthesis of the alkaloid dihydropinidine, as well as its enantiomer, by choosing an appropriate ω‐transaminase
Ruthenium-Catalyzed C6-Propenylation Reactions of Substituted Pyridine Derivatives: Directed and Direct CH Activation
作者:Yogesh Goriya、Chepuri V. Ramana
DOI:10.1002/chem.201202379
日期:2012.10.15
One stone, two birds: Aryl pyridine derivatives in the presence of allyl bromide and a catalytic amount of [Ru(p‐cymene)Cl2}2] undergo an unexpected direct C6‐propenylation reaction of the pyridine moiety. A one‐pot one‐catalyst three‐component reaction involving sequential and selective direct and directed CH activation reactions was also developed (see scheme).
Asymmetric synthesis of (+)- and (−)-dihydropinidines: diastereoselective addition to chiral imine or 1,3-oxazolidine derived from (R)-phenylglycinol as a single starting material with organometallic reagents
construction of bothenantiomers of the natural products by using a singlechiral source, (R)-phenylglycinol. Bothroutes were carried out by similar processes, except for either the presence of an imine or 1,3-oxazolidine intermediate. Excellent diastereoselectivity was observed in the reaction of chiral imines and 1,3-oxazolidines with organometallic reagents, to give the chiral amines in high chemical
Cross-Metathesis of Chiral <i>N</i>-<i>tert</i>-Butylsulfinyl
Homoallylamines: Application to the Enantioselective Synthesis of
Naturally Occurring 2,6-<i>cis</i>-Disubstituted Piperidines
The synthesis of piperidine alkaloids (+)-dihydropinidine (1), (+)-isosolenopsin (2a), (+)-isosolenopsin A (2b), and (2R,6R)-6-methylpipecolic acid (3a) hydrochlorides, based on cross-metathesis of chiral N-tert-butylsulfinyl homoallylamines with methyl vinyl ketone, is presented.