Ruthenium‐catalyzed carbonylative cycloaddition reactions involving carbonyl and imino groups as assembling units

Abstract

This paper describes carbonylative cycloaddition reactions catalyzed by Ru3(CO)12. Ru3(CO)12 was found to catalyze an intramolecular Pauson-Khand-type reaction. Carbonylative cycloaddition reactions involving a carbonyl group in aldehydes, ketones, and esters as a two-atom assembling unit were also achieved in the presence of Ru3(CO)12 as the catalyst. The reaction of 5-hexyn-1-al and 6-heptyn-1-al derivatives with CO in the presence of Ru3(CO)12 resulted in cyclocarbonylation from which bicyclic alpha, beta-unsaturated lactones were obtained. Intermolecular [2 + 2 + 1] carbonylative cycloaddition of alkenes, ketones, and CO was also catalyzed by Ru3(CO)12 as the catalyst to give saturated gamma-lactone derivatives. Simple ketones were not applicable, but ketones having a C==O or C==N group at the alpha-position served as a good substrate. These reactions could be extended to carbonylative cycloaddition of the corresponding imines leading to gamma-butyrolactam derivatives. The [4 + 1] carbonylative addition of alpha,beta-unsaturated imines leading to unsaturated gamma-lactams was achieved with Ru3(CO)12.

Formation of Polycyclic Lactones through a Ruthenium-Catalyzed Ring-Closing Metathesis/Hetero-Pauson–Khand Reaction Sequence

“…The ruthenium-catalyzed HPK work described by Murai indicates that olefin isomerization can, at times, lead to undesired side products . To test whether this would be an issue with our tandem process, we prepared and tested substrates in which an allylic ether linkage is present in the ring generated through RCM.…”

“…The Murai group, in particular, explored the scope of the ruthenium-catalyzed HPK reaction . Inter- and intramolecular examples of this ruthenium-catalyzed transformation are illustrated in eqs and .…”

Progress in Carbonylative [2+2+1] Cycloaddition: Utilization of a Nitrile Group as the π Component

“…In contrast, these reactions would generally be referred to as the hetero‐Pauson–Khand‐type reaction (HPKTR) if more than one carbon atom of the newly generated cyclopentenone framework of B was replaced by an oxygen atom or nitrogen functionalities. Both ketone3 and aldehyde3f, 4 groups (oxa‐alkene π bond) have been employed in this context, and the imine functionalities3f, 4c, 5 were shown to serve as the aza‐alkene π bond. Furthermore, the carbodiimide groups (diaza‐allene)6 provided an alternative aza‐alkene π bond.…”

Formal [4+1] Annulation Reactions in the Synthesis of Carbocyclic and Heterocyclic Systems

“…The catalytic carbonylative [4+1] cycloaddition of α,β-unsaturated imines with CO is a challenging but synthetically useful method for the construction of γ-lactam skeletons, which are commonly found in numerous alkaloids and pharmaceutically promising compounds. Murai and his co-workers developed the first example of a [4+1] cycloaddition of structurally simple α,β-unsaturated imines 31 with CO catalyzed by Ru 3 (CO) 12 (Scheme ) . These authors noted that the selection of t Bu group of the nitrogen atom and the use of 10 atm of CO at 180 °C were critical for the reaction efficiency.…”