A concise total synthesis of (+)-deoxocassine and (−)-deoxoprosophylline from d-xylose
摘要:
A concise total synthesis of (+)-deoxocassine (1) and (-)-deoxoprosophylline (2) has been achieved for the first time from D-xylose. The key steps involved in these synthesis are alkyl Grignard reaction, S(N)2 substitution of mesylate by azide, Wittig reaction, and reductive amination. (C) 2012 Elsevier Ltd. All rights reserved.
A Route to “all-cis” 2-Methyl-6-Substituted Piperidin-3-ol Alkaloids from syn-(2R,1′S)-2-(1-Dibenzylaminomethyl)epoxide: Rapid Total Synthesis of (+)-Deoxocassine
作者:Pierre-Yves Géant、Jean Martínez、Xavier J. Salom-Roig
DOI:10.1002/ejoc.201101333
日期:2012.1
to the synthesis of two cis-2-methyl-6-substituted piperidin-3-ols is described. syn-(2R,1′S)-2-(1-Dibenzylaminomethyl) epoxide (13) was used as common building block. The key step involved oxirane ring opening of 13 by the nucleophilic lithium aza-enolate of hydrazones 12a and 12b. Subsequent hydrazone hydrolysis and intramolecular reductive amination afforded the alkaloid (+)-deoxocassine and a new
One-pot multiple reactions: asymmetric synthesis of 2,6-cis-disubstituted piperidine alkaloids from chiral aziridine
作者:Nagendra Nath Yadav、Jihye Choi、Hyun-Joon Ha
DOI:10.1039/c6ob00806b
日期:——
A divergent, new, and highly stereoselective synthesis of cis-2,6-disubstituted piperidine natural products including isosolenopsins, deoxocassine, and spectaline was achieved from chiral aziridine decorated with appropriate alkyl chains for isosolenopsins or alkynyl groups for deoxocassine and spectaline at C2. The characteristic feature of this synthesis is one-pot sequential reactions under atmospheric
A modified Kondrat’eva cycloaddition involving an unprecedented thermally controlled metal-free decarboxylative aromatization affords an expedient access to natural 3-hydroxypyridine/piperidine systems.
Application of the Aza-Achmatowicz Oxidative Rearrangement for the Stereoselective Synthesis of the <i>Cassia</i> and <i>Prosopis</i> Alkaloid Family
作者:Carolyn A. Leverett、Michael P. Cassidy、Albert Padwa
DOI:10.1021/jo0616714
日期:2006.10.1
uted piperidin-3-ol alkaloids of the Cassia and Prosopis species are readily prepared by a combination of an aza-Achmatowicz oxidative rearrangement and dihydropyridone reduction followed by a stereoselective allylsilane addition to a N-sulfonyliminium ion. The stereochemical outcome of the reduction reaction can be attributed to steric hindrance between the pseudoaxially oriented 2,6-substituents
决明和Prosopis物种的顺式 -2-甲基-6-取代的哌啶-3-醇生物碱很容易通过结合氮杂-Achmatowicz 氧化重排和二氢吡啶酮还原,然后将立体选择性烯丙基硅烷加成到N-磺酰亚胺离子上来制备。还原反应的立体化学结果可归因于假轴取向的2,6-取代基和赤道接近的氢化物试剂之间的空间位阻,这解释了通过氢化物的轴向接近而排他地形成顺式醇。通过催化还原除去( E )-甲基-戊-3-烯酸酯侧链中存在的不饱和度,并将剩余的酯基转化为相应的Weinreb's酰胺。该关键中间体用于合成阿齐米酸、脱氧卡辛、酪氨酸和香料。( S )-N-甲苯磺酰氨基呋喃16的简便制备及其向手性 Achmatowicz 氧化产物18 的转化提供了这些生物碱的正式手性合成。