Desymmetrization of spiro-activated meso-cyclopropanes via nucleophilic substitution
摘要:
The spiro-activated cyclopropane 1 undergoes desymmetrization either with Li-thiophenoxide in the presence of a chiral complexing ligand, or with ion pairs formed from thiophenols and aromatic chiral amines. The latter procedure is more efficient and provides the ring-opened thioether 6 in up to 79% yield and up to 60% ee. (c) 2005 Elsevier Ltd. All rights reserved.
Desymmetrization of spiro-activated meso-cyclopropanes via nucleophilic substitution
摘要:
The spiro-activated cyclopropane 1 undergoes desymmetrization either with Li-thiophenoxide in the presence of a chiral complexing ligand, or with ion pairs formed from thiophenols and aromatic chiral amines. The latter procedure is more efficient and provides the ring-opened thioether 6 in up to 79% yield and up to 60% ee. (c) 2005 Elsevier Ltd. All rights reserved.
Blue LED Irradiation of Iodonium Ylides Gives Diradical Intermediates for Efficient Metal‐free Cyclopropanation with Alkenes
作者:Tristan Chidley、Islam Jameel、Shafa Rizwan、Philippe A. Peixoto、Laurent Pouységu、Stéphane Quideau、W. Scott Hopkins、Graham K. Murphy
DOI:10.1002/anie.201908994
日期:2019.11.18
A facile and highly chemoselective synthesis of doubly activated cyclopropanes is reported where mixtures of alkenes and β-dicarbonyl-derived iodoniumylides are irradiated with light from blue LEDs. This metal-free synthesis gives cyclopropanes in yields up to 96 %, is operative with cyclic and acyclic ylides, and proceeds with a variety of electronically-diverse alkenes. Computational analysis explains