Enantioselective, (−)-sparteine-mediated deprotonation of geranyl and neryl N,N-diisopropylcarbamate: configurational stability of the intermediate lithium compounds
摘要:
(E)/(Z) 异构的邻位复碳酸酯均由 n-乙基Li 和 (-)- paylaşine 在toluene中脱质子化。通过捕获实验使用氯 triflate 得到α-取代产物,并发现这些产物具有 (R)构型,这表明 S 端的质子被优先去掉而形成相应的 (S)-Li (.) (−)-`;
等产物;实验结果表明k(s)/k(R) 值分别大于15:1和7:1。在−78°C下,发生 S-R 型转置反应的速度非常慢,且半衰期大于60 min。邻位双键在这些条件下对(Z)-(E)异构稳定。 (c)2005 Elsevier Ltd. All rights reserved.
Enantioselective, (−)-sparteine-mediated deprotonation of geranyl and neryl N,N-diisopropylcarbamate: configurational stability of the intermediate lithium compounds
摘要:
(E)/(Z) 异构的邻位复碳酸酯均由 n-乙基Li 和 (-)- paylaşine 在toluene中脱质子化。通过捕获实验使用氯 triflate 得到α-取代产物,并发现这些产物具有 (R)构型,这表明 S 端的质子被优先去掉而形成相应的 (S)-Li (.) (−)-`;
等产物;实验结果表明k(s)/k(R) 值分别大于15:1和7:1。在−78°C下,发生 S-R 型转置反应的速度非常慢,且半衰期大于60 min。邻位双键在这些条件下对(Z)-(E)异构稳定。 (c)2005 Elsevier Ltd. All rights reserved.
Stereospecific conversion of alcohols into pinacol boronic esters using lithiation–borylation methodology with pinacolborane
作者:Stefan Roesner、Christopher A. Brown、Maziar Mohiti、Alexander P. Pulis、Ramesh Rasappan、Daniel J. Blair、Stéphanie Essafi、Daniele Leonori、Varinder K. Aggarwal
DOI:10.1039/c4cc00993b
日期:——
The synthesis of primary and secondary pinacol boronic esters via lithiation–borylation of carbamates and benzoates with pinacolborane is described.
通过对氨基甲酸酯和苯甲酸酯进行锂化-硼化反应,使用二甲基二醇硼烷合成初级和次级的丙二醇硼酸酯。
Synthesis and deprotonation of 1-(p-toluenesulfonyl)-2-al-kenyl carbamates. Dichotomous achiral d1 and chiral d3 reagents for carbonyl addition directed by metal exchange
作者:Michael Reggelin、Petra Tebben、Dieter Hoppe
DOI:10.1016/s0040-4039(00)99157-3
日期:1989.1
title compounds 3 were prepared by electrophilic sulfonylation of allylic carbamates 1. The achiral lithium anions 4 add to carbonyl compounds with the α-position, thus permitting nucleophilic alkenoylation, whereas the chiral titanium derivates 8 undergo completely regioselective γ-addition, representing a new class of homoenolate reagents.
Total Syntheses of (−)-Transtaganolide A, (+)-Transtaganolide B, (+)-Transtaganolide C, and (−)-Transtaganolide D and Biosynthetic Implications
作者:Hosea M. Nelson、Jonny R. Gordon、Scott C. Virgil、Brian M. Stoltz
DOI:10.1002/anie.201301212
日期:2013.6.24
‘Dibal'lin’ on a budget: The enantioselective total syntheses of transtaganolides A–D are rapidly achieved by a highly diastereoselective Ireland–Claisen/Diels–Alder cascade reaction of an enantioenriched geraniol derivative (see scheme). Based on X‐ray diffraction data, the absolute configuration of these metabolites is established and discussed within the context of existing biosynthetic hypotheses
预算中的“Dibal'lin”:通过对映体富集的香叶醇衍生物的高度非对映选择性爱尔兰-克莱森/狄尔斯-阿尔德级联反应快速实现转塔格内酯 A-D 的对映选择性全合成(参见方案)。基于 X 射线衍射数据,在现有生物合成假设的背景下建立并讨论了这些代谢物的绝对构型。
REGGELIN, MICHAEL;TEBBEN, PETRA;HOPPE, DIETER, TETRAHEDRON LETT., 30,(1989) N2, C. 2915-2918
作者:REGGELIN, MICHAEL、TEBBEN, PETRA、HOPPE, DIETER
DOI:——
日期:——
Enantioselective, (−)-sparteine-mediated deprotonation of geranyl and neryl N,N-diisopropylcarbamate: configurational stability of the intermediate lithium compounds
作者:Wenbin Zeng、Roland Fröhlich、Dieter Hoppe
DOI:10.1016/j.tet.2005.01.100
日期:2005.3
(E)/(Z)-Isomeric allylic carbamate esters were deprotonated by n-butyllithium/(-)-sparteine in toluene. Trapping experiments with chlorotrimethylsilane afforded the alpha-substitution products, with (R)-configuration, revealing that the pro-S proton is removed predominantly to form the corresponding (S)-lithium (.) (-)-sparteine derivatives; k(s)/k(R) > 15:1 and > 7: 1, respectively. A slow (S) -> (R)-epimerization occurs at - 78 degrees C (T-1/2 > 60 min). The allylic double bond is stable to (Z)-(E) isomerization under these conditions. (c) 2005 Elsevier Ltd. All rights reserved.
(E)/(Z) 异构的邻位复碳酸酯均由 n-乙基Li 和 (-)- paylaşine 在toluene中脱质子化。通过捕获实验使用氯 triflate 得到α-取代产物,并发现这些产物具有 (R)构型,这表明 S 端的质子被优先去掉而形成相应的 (S)-Li (.) (−)-`;
等产物;实验结果表明k(s)/k(R) 值分别大于15:1和7:1。在−78°C下,发生 S-R 型转置反应的速度非常慢,且半衰期大于60 min。邻位双键在这些条件下对(Z)-(E)异构稳定。 (c)2005 Elsevier Ltd. All rights reserved.