Rh(III)-Catalyzed C–H Activation-Initiated Directed Cyclopropanation of Allylic Alcohols

Abstract

We have developed a Rh(III)-catalyzed diastereoselective [2+1] annulation onto allylic alcohols initiated by alkenyl C-H activation of N-enoxyphthalimides to furnish substituted cyclopropylketones. Notably, the traceless oxyphthalimide handle serves three functions: directing C-H activation, oxidation of Rh(III), and, collectively with the allylic alcohol, in directing cyclopropanation to control diastereoselectivity. Allylic alcohols are shown to be highly reactive olefin coupling partners leading to a directed diastereoselective cyclopropanation reaction, providing products not accessible by other routes.

An α‐Cyclopropanation of Carbonyl Derivatives by Oxidative Umpolung

“…The syntheses of cyclopropanes are often mediated by metals, but metal free approaches are also known such as the Johnson–Corey–Chaykovsky reaction . Several reviews have been published .…”

“…Although trans selectivity for the cyclopropanation was excellent and yields were typically higher, the reaction showed no selectivity over a third stereogenic center in the cyclopropylcarbinyl position (16 mb), possibly a result of the intermediacy of a highly stabilized tertiary cyclopropylcarbinyl cation. [61] The syntheses of cyclopropanes are often mediated by metals, [62][63][64] but metal free approaches are also known [65,66] such as the Johnson-Corey-Chaykovsky reaction. [67,68] Several reviews have been published.…”

Iridium(III) Catalysts with an Amide‐Pendant Cyclopentadienyl Ligand: Double Aromatic Homologation Reactions of Benzamides by Fourfold C−H Activation

“…Although Satoh, Sato, Miura, and coworkers, as well as Li and co-workers have reported this type of reaction using a Cp*Rh III catalyst, the applicable substrates were limited to those bearing a strongly coordinating azoletype directing group. [12a,d,e] [2][3][4][5]. We speculate that the poor reactivity of 5 b might be due to its poor solubility, and the more electron-deficient nature of 5 e might lead to low stability.…”

“…[1d,e] On the other hand, as electronic and steric effects of ancillary ligands are also important factors in metal-catalyzed transformations, several research groups have developed modified Cp ligands to achieve high and/or unique reactivity and selectivity. [2][3][4][5][6][7][8][9] Aside from steric modifications that forge a steric bias around the piano-stool structure of CpM III complexes, [2] including chiral Cp x ligands for enantioselective reactions, [3] the introduction of electron-withdrawing groups on the Cp ligands to render the metal catalysts electron-deficient is the most successful approach (Figure 1 b). [2, 4, 5, 6a,b, 7, 8] Rovis and co-workers have developed a series of Rh III catalysts that bear electronically tuned Cp ligands and examined their catalytic properties, [2,5] revealing that Cp* CF3 Rh III catalysts exhibit higher reactivity in [4+2] annulation reactions of oxime derivatives to provide (dihydro)pyridines by olefinic CÀH activation.…”

Enantioselective CpxRhIII‐Catalyzed Carboaminations of Acrylates

“…[12] Our group previously demonstrated the utility of related enoxysuccinimide substrates [13] in Cp x Rh IIIcatalyzed enantioselective cyclopropanations of acrylates. [14,15] Chiral Cp x ligands demonstrated a broad applicability for enantioselective functionalizations [16] of aryl CÀH bonds [17] and more recently for alkenyl CÀH bonds. [18] We therefore hypothesized that a different chiral Cp x ligand may allow diversion of the reaction pathway from a cyclopropanation to an enantioselective carboamination.…”