215872-27-8Relevant academic research and scientific papers
REACTIONS OF COORDINATED CYCLIC POLYOLEFINS. REGIO- AND STEREO-SPECIFIC CYCLOADDITIONS OF KETENES AND TRICARBONYL(η4-POLYENE)IRON COMPLEXES. STRUCTURAL EVIDENCE FOR A CONCERTED 2 + 2 MECHANISM
Goldschmidt, Zeev,Antebi, Shlomo,Cohen, Drora,Goldberg, Israel
, p. 347 - 360 (2007/10/02)
The cycloaddition of ketenes R1R2C=C=O (R1 = Me, R2 = Ph; R1 = R2 = Ph; R1 = Ph, R2 = p-tolyl) (III) and tricarbonyl(η4-cycloheptatriene)iron (II) at room temperature gave regiospecifically the cyclobutanones IV, in which the carbonyl is bonded to the uncoordinated terminal of the conjugated triene.Tricarbonyl(η4-cyclooctatetraene)iron.VI, similarly reacts with diphenylketene to give the regioisomeric cyclobutanone VIII.Single crystal X-ray analysis of tricarbonylnonan-2,4-dien-8-one>iron (IVa) confirmed the presence of the phenyl group at the endo position, providing a stereochemical evidence for a concerted 2s + 2a cycloaddition mechanism.The adducts IV undergo cyclobutanone ring cleavage catalyzed by acid to give the isomeric ketones VII.The diaryl adducts (IVb and IVc) rearrange thermally to the ?,?-allylic complexes IX, which may also be obtained directly upon heating cycloheptatriene complex II and the diarylketenes.
