Gold‐Mediated Isomerization of ­Cyclooctyne to Ring Fused Olefinic Bicycles

Abstract

Isomerization reactions of cyclooctyne mediated by N-heterocyclic carbene supported gold(I) leading to ring-contraction and the formation of 5/5-fused bicyclic alkenes have been observed. Isolation and complete characterization, includ-

Nickel Hydride Complexes Supported by a Pyrrole-Derived Phosphine Ligand

“…The product composition was determined by NMR and gas chromatography–mass spectrometry (GC-MS). The 1 H and 13 C­{ 1 H} NMR spectra for the individual isomers match those previously reported ( A : cis -bicyclo­[3.3.0]­oct-2-ene, B : bicyclo[3.3.0]­oct-1(2)-ene, C : bicyclo[3.3.0]­oct-1(5)-ene, ,, D : 1,4-cyclooctadiene, E : 1,3-cyclooctadiene).…”

Gold-Catalyzed Homogeneous (Cyclo)Isomerization Reactions

“…Nonetheless, cycloisomerization processes have also been described in molecules containing solely a reactive alkyne or alkene group. This is the case of the gold(I)-directed ring-contraction process of cyclooctyne to 5-member bicyclic alkenes (Das et al, 2016) or the intramolecular hydroamination of 6-alkenyl-2-pyridones to yield 1,6-carboannulated 2-pyridones (Timmerman et al, 2017). In those circumstances where both types of unsaturations are present, the well-known preference of gold for alkyne over alkene groups is rationalized in terms of the HOMO-LUMO energy gap of the coordinated π-systems rather than through intrinsic considerations of the metal itself (Gorin and Toste, 2007).…”