Described herein is a visible-light mediated intermolecular radicalcyclization approach to access heterocycles. Heteroatom radicals, such as silicon and phosphorus atom radicals, were generated via direct hydrogen atom abstraction by the photoexcited catalyst species with hydro-silanes and phosphineoxides. The radical addition/cyclization/HAT (hydrogen atom transfer) reaction sequences of 1,6-enynes
Silver‐Free Au(I) Catalysis Enabled by Bifunctional Urea‐ and Squaramide‐Phosphine Ligands via H‐Bonding
作者:Allegra Franchino、Àlex Martí、Stefano Nejrotti、Antonio M. Echavarren
DOI:10.1002/chem.202101751
日期:2021.8.16
A library of gold(I) chloride complexes with phosphine ligands incorporating pendant (thio)urea and squaramide H-bond donors was prepared with the aim of promoting chloride abstraction from Au(I) via H-bonding. In the absence of silver additives, complexes bearing squaramides and trifluoromethylated aromatic ureas displayed good catalytic activity in the cyclization of N-propargyl benzamides, as well
Enantioselective Alkoxycyclization of 1,6‐Enynes with Gold(I)‐Cavitands: Total Synthesis of Mafaicheenamine C
作者:Inmaculada Martín‐Torres、Gala Ogalla、Jin‐Ming Yang、Antonia Rinaldi、Antonio M. Echavarren
DOI:10.1002/anie.202017035
日期:2021.4.19
cyclization has been applied for the first totalsynthesis of carbazole alkaloid (+)‐mafaicheenamine C and its enantiomer, establishing its configuration as R. The cavity effect was also evaluated in the cycloisomerization of dienynes. A combination of experiments and theoretical studies demonstrates that the cavity of the gold(I) complexes forces the enynes to adopt constrained conformations, which results