Palladium‐Mediated [2+1] Cycloaddition of Norbornene Derivatives with Ynamides

Abstract

International audienceAn efficient palladium-catalyzed [2 + 1]cycloaddition between ynamides and norbornenes or norbornadienes is reported. Both phosphapalla- dacycles and palladium/secondary phosphine oxide catalytic systems were found to be competent for the transformation allowing the preparation of ami- nomethylenecyclopropanes. The reaction showed general applicability to various functionalized bicyclo[2.2.1]hept-2-enes and ynamides. A chiral phosphapalladacycle was tested to carry out this transformation in an enantioselective fashion

Highly Selective Syn Addition of 1,3‐Diones to Internal Ynamides Catalyzed by Zinc Iodide

“…Unfortunately, the stereochemistry of the carbon–carbon double bond was not clearly discussed (Scheme a). During the course of our research, directed toward the use of ynamides in [2+1] cycloadditions, we discovered that the Herrmann–Beller catalyst ( H‐B cat ) was able to promote the hydroalkoxylation of ynamides with 1,3‐diones . Although good yields were obtained with terminal ynamides (Scheme b), the resulting products were easily hydrolysable under acidic conditions.…”

The Applications of Palladacycles as Transition-Metal Catalysts in Organic Synthesis

“…On the basis of these clues and reports in the literature, 9,33 we proposed a plausible mechanism for the transformation (Scheme 18 The regioselective synthesis of polysubstituted furans by the palladacycle-catalyzed reaction of bicyclic alkenes with terminal ynones suggested to us that polysubstituted pyrroles might be obtained from an alkynyl imine as the reactant. Indeed, the reaction of 1,4-dihydro-1,4-epoxynaphthalene (4a) with alkynyl imine 30a did proceed smoothly in the presence of palladacycle 18.…”

[2+1] Cycloaddition Affording Methylene- and Vinylidenecyclopropane Derivatives: A Journey around the Reactivity of Metal-Phosphinito-Phosphinous Acid Complexes

“…Because aminomethylenecyclopropanes 7 are known to possess interesting biological activities, we studied the possibility of preparing them by [2+1] cycloaddition using ynamides as partners . The reaction conditions, and mainly the nature of the palladium‐based catalyst, were investigated using norbornadiene and N ‐phenyl‐ N ‐tosylynamide (Table ).…”

“…Having synthesized enantiopure phosphapalladacycle 1f , we decided to evaluate it in asymmetric [2+1] cycloaddition with ynamide and norbornadiene (Scheme ) . Complex 1f displayed good activity, since the expected ACP 7a was obtained in a good yield of 80 %.…”