NMR studies on the structure of a lithium amide–chiral diether complex for an asymmetric reaction
摘要:
The combination of a chiral diether ligand and a lithium benzyl(trimethylsilyl)amide is a powerful lithium amide reagent for asymmetric conjugate amination of enoate in a toluene solvent. The structure of the chiral diether-lithium amide complex in solution was analyzed by low-temperature NMR. Li-6 NMR suggested the formation of a cyclic heterodimer. The stereochemical pathway is predictable based on the structure of the lithium amide chiral diether complex. (C) 2013 Elsevier Ltd. All rights reserved.
together now: A commonintermediate of Kopsia alkaloids was synthesized from cis‐2,3‐disubstituted piperidine, which was obtained with 98 % ee in 85 % yield using chiral diether‐controlled asymmetric conjugate addition of lithium amide to indolepropenoate, followed by C,N dual alkylation with 1‐chloro‐3‐iodopropane. The synthesis of (−)‐kopsinine was accomplished via the intermediate in 9.0 % overall
Studies on total synthesis of cylindrospermopsin: new constructions of uracils from α,β-unsaturated esters
作者:Stephen P Keen、Steven M Weinreb
DOI:10.1016/s0040-4039(00)00633-x
日期:2000.6
Two different routes have been developed to prepare uracils related to that found in the marine hepatotoxin cylindrospermopsin starting from α,β-unsaturated esters.
Synthesis of substituted pyrroles via zirconocene complexes of imines
作者:Stephen L. Buchwald、M. Woods Wannamaker、Brett T. Watson
DOI:10.1021/ja00184a080
日期:1989.1
Syntheses a partir du complexe chloro de Zr-methyl zirconocenevia la reaction de CO avec des alkyl-3 aryl-5 trimethylsilyl-1 di-η 5 -cyclopentadienyl-2,2 aza-1zircona-2cyclopentenes-3
通过la反应合成partir du complexe chloro de Zr-methyl zirconocene via de CO avec des烷基-3 aryl-5 trimethylsilyl-1 di-η 5 -cyclopentadienyl-2,2 aza-1zircona-2cyclopentenes-3
Stereoselective α-alkylation of α,β-unsaturated esters utilizing conjugate addition of nitrogen nucleophiles (R<sub>2</sub>NLi)
作者:Tadao Uyehara、Naoki Asao、Yoshinori Yamamoto
DOI:10.1039/c39870001410
日期:——
Treatment of α,β-unsaturatedesters (1) with lithium amides [LiNPri2 and LiN(CH2Ph)SiMe3] followed by alkylation and elimination of the amino groups produced trisubstituted enoates (2) with high stereoselectivity.
用酰胺化锂[LiNPr i 2和LiN(CH 2 Ph)SiMe 3 ]处理α,β-不饱和酯(1),然后烷基化并消除氨基基团产生具有高立体选择性的三取代烯酸酯(2)。
(<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine as Chiral Auxiliary in Asymmetric Aza-Michael Reactions. Unexpected Selectivity Change when Manipulating the Structure of the Auxiliary
作者:Juan Etxebarria、Jose L. Vicario、Dolores Badia、Luisa Carrillo、Nerea Ruiz
DOI:10.1021/jo051207j
日期:2005.10.1
the structure of the chiralauxiliary, which has allowed a diastereodivergent procedure to be set up for performing asymmetric aza-Michael reactions using the same chirality source. Finally, the adducts obtained in the asymmetric aza-Michael reaction have proven to be very versatile synthetic intermediates in the preparation of other interesting compounds such as β-amino esters, γ-amino alcohols, and