N-Heterocyclic Carbene Catalyzed Ring Expansion of Formylcyclopropanes: Synthesis of 3,4-Dihydro-α-pyrone Derivatives
摘要:
N-Heterocyclic carbene catalyzed ring expansion of readily accessible 2-acyl-l-formylcyclopropanes was developed. With 5 mol % of triazoliurn salt 5 and 30 mol % of DBU, ring expansion of various 2-acyl-l-formylcyclopropanes led to 3,4-dihydro-alpha-pyrones in good to excellent yields.
Chiral cyclopentadienyl Rh<sup>III</sup>-catalyzed enantioselective cyclopropanation of electron-deficient olefins enable rapid access to UPF-648 and oxylipin natural products
作者:Coralie Duchemin、Nicolai Cramer
DOI:10.1039/c8sc05702h
日期:——
Chiral cyclopentadienyl RhIII complexes efficientlycatalyze enantioselective cyclopropanations of electron-deficient olefins with N-enoxysuccinimides as the C1 unit. Excellent asymmetric inductions and high diastereoselectivities can be obtained for a wide range of substrate combinations. The reaction proceeds undermildconditions without precautions to exclude air and water. Moreover, the synthetic
N-Heterocyclic carbene catalyzed C-acylation reaction for access to linear aminoenones
作者:Jie Lv、Yingling Nong、Kai Chen、Qingyun Wang、Jiamiao Jin、Tingting Li、Zhichao Jin、Yonggui Robin Chi
DOI:10.1016/j.cclet.2022.05.084
日期:2023.1
An N-heterocycliccarbene (NHC)-catalyzed carbonyl nucleophilic substitution reaction between 1-cyclopropylcarbaldehydes and N-sulfonyl imines is developed for access to linear β-aminoenone products. The β-aminoenones containing cyclopropyl fragments can be afforded in moderate to excellent yields under mild conditions. The reaction features excellent trans-diastereoselectivities and the desired aminoenone
precursors or key reaction intermediates benefits the development of a wide range of reactions. Herein, we report a facile protocol for the synthesis of this compound through gold-catalyzed [2 + 1] cycloaddition of allenamides with sulfoxonium ylides. The reaction exhibited good functional group tolerance and high efficiency, affording the products in good to excellent yields with good diastereoisomerism