Asymmetric synthesis of 2-substituted butane-1,4-diols by hydrogenation of homochiral fumaramide derivatives
摘要:
Diastereoselective hydrogenation of homochiral fumaramides 1 derived from (2R)-Oppolzer's sultam was observed by analysis of the H-1 NMR spectra of the succinamide mixtures with de's of 77-88%. Reduction of these succinamides using LiAlH4 gave the corresponding (2S)-butane-1,4-diols and established that addition of hydrogen takes place selectively on the re-face of 14 fumaramides 1. The stereoselectivity was confirmed by estimating the ee's from the F-19 NMR spectra of the Mosher's diesters of the diols. This methodology was applied to the synthesis of selected pyrrolidine natural products in homochiral form. (C) 2004 Elsevier Ltd. All rights reserved.
Leveraging the n→π* Interaction in Alkene Isomerization by Selective Energy Transfer Catalysis
作者:Tomáš Neveselý、John J. Molloy、Calum McLaughlin、Linda Brüss、Constantin G. Daniliuc、Ryan Gilmour
DOI:10.1002/anie.202113600
日期:2022.1.10
Fumarate to maleate (E→Z) isomerization was investigated to validate nO→ πC=O* interactions as a driving force for contra-thermodynamic isomerization. A general protocol based on selective energy transfer catalysis was developed with inexpensive thioxanthone as a sensitizer for the conversion of diverse fumarate derivatives, including tetrasubstituted alkenes. The involvement of nO→πC=O* interactions
研究了富马酸到马来酸 ( E → Z ) 异构化,以验证 n O → π C=O * 相互作用作为反热力学异构化的驱动力。采用廉价的噻吨酮作为敏化剂,开发了基于选择性能量转移催化的通用方案,用于转化各种富马酸酯衍生物,包括四取代烯烃。 X 射线晶体学证实了 n O →π C=O * 相互作用的参与。
COOKE M. P., TETRAHEDRON LETT., 1981, 22, NO 5, 381-384